Diane

is a member of the Seven Deadly Sins and is known as the Serpent's Sin of Envy. She is a member of the Giant Clan, and is thus much larger than ordinary people, including her fellow Deadly Sins. Her Sacred Treasure is the War Hammer Gideon, which she uses in conjunction with her inherent power, Creation.

Appearance
As a giant, Diane is several times larger than an ordinary human being. She is a fair maiden, described as "lovely, beautiful" with purple eyes and medium length brown hair which is tied up into large twin tails. She has a well-developed and curvaceous body. Similar to most of the other Seven Deadly Sins, her facial appearance is relatively childlike and has shown little change over the years. Diane's wanted poster depicts her with light colored hair. Her symbol, which is of the Serpent, is located on her left outer thigh.

When she was still a child, Diane wore ragged clothing until King made her a new set. Her clothes during the earlier part of the series resembles what King made for her, having sewn it herself by using leather derived from Dusk Bison skin. Her earlier attire consisted of a short-sleeved one-piece orange suit, boots with five crossed laces that extend almost up to her knees, and two finger-less gauntlets of a blue-grey leathery material covered in shiny steel stud - with the right gauntlet having been destroyed by Gilthunder during the fight in the Forest of White Dreams. She also wore a backpack previously used by Meliodas.

Ten years ago, Diane—as a Holy Knight—wore a full body orange armor with a unique helmet like the rest of her fellow Deadly Sins.

Diane's current clothes is made by Merlin and is almost the same style as her previous one, except for an inverted triangle cut on the chest, and the skirt. She is also wearing black underwear underneath the skirt.

Personality
Diane is a very friendly woman, and is also very confident regarding her abilities, appearing to generally consider Holy Knights as weak. She cares very much about her captain and holds very strong feelings for Meliodas, often cuddling him and becoming very delighted from compliments. Her feelings are strong enough for her to overcome her fears for his sake. However, she is very quick to throw temper tantrums, and often does so upon becoming upset. Diane also gets angry and jealous when Meliodas does perverted things to other girls.

Due to her size, she cannot help Meliodas in any way other than fight for him. She has expressed her strong desire to be smaller, contrary to Elizabeth's desire to be strong. Despite Diane stating that she has no interest in humans, she still selflessly saves people who are in danger, like when the elderly man in Vaizel and Zeal were at risk, Diane risked her life to protect them.

Despite her brave and strong appearance, Diane is a somewhat emotionally fragile person, as shown by her hatred of loneliness. This was portrayed when she was a child and insisted that King stay by her side when she was sick instead of getting herbs to heal her, and when she waited in tears for him to return to her. Diane showed the same kind of feelings towards Elizabeth after she was kidnapped by Vivian. Whenever nervous or embarrased, she covers her mouth with one of her pigtails and blushes.

700 years ago
Many years ago, Diane left the Giant's Clan due to her hatred for fighting. After her departure, she formed two rock-like golems to accompany her, despite either of them being unable to talk. She was always alone playing with them as there were no other living beings who would accept her.

At one time however; Diane found an injured King lying unconscious on a riverbank and nursed the fairy back to health. King, who had taken a hard blow to his head, had lost all memories of his past and in his gratitude spent the next five hundred years playing with and protecting Diane. Diane later met an old man, a human, who offered Diane and King some food despite them being Fairy and a Giant. King was wary with the old man, and told Diane to be careful around humans. Due to unknown reasons, Diane ended up getting a fever, in which King panicked due to Fairies never having fevers and went out to get herbs. However, Diane stopped him, telling him to not ever leave her side since she didn't want to be alone anymore. The old man who gave them food found them, and concocted a herbal medicine for Diane's fever, eventually curing her of her ailment. As soon as Diane got better, King and Diane ended up playing tag with each other, as King told her that if she caught him, he will grant her a wish.

Diane took it seriously and caught King, but ended up getting her clothes ripped off in the fray, leaving her entirely naked, much to King dismay. King end up making her new clothes and the two went to visit the old man hunter's place, only to find more houses had sprung up around there, and that the man they believed was the hunter they had met was actually the late hunter's grandson. After leaving the forest, King told Diane about marriage between two humans who love each other. Diane asked if King loves her, which he flushed to, but agreed. Diane thus chose to use King's promise to make him always love her. He agreed wholeheartedly. Later that night, King ended up remembering who he is through various flashbacks in his dreams, and found out that the village close by was on fire. King told Diane to stay back as he went to the town, promising to come back. Diane waited in tears, hoping for King to return, only to find King return and strike her with a flower to her spine to erase her memories of him. Diane eventually awoke from her slumber without any memories, but curiously picked up King's flower and walked outside. She rejoins the Giant's Clan afterwards.

15 years ago
Several hundred years later, Diane had grown into a woman, and was in midst of being trained by Matrona to become the strongest Giant warrior alongside another fellow giantess, Dolores. One evening, Diane overheard Matrona's plans to make Diane the strongest Giant warrior ever. Disliking Matrona's plans for her, Diane made up her mind to leave the village once more. She goes to find Dolores and run away with her, but Dolores declines. Dolores explains after much thought, the Giant's village is the only place where they'll ever be accepted, and that there was nothing to fear once you've been accepted.

Diane left the village once more alone, and soon entered into a petty argument with a group of knights called the Knights of the Golden Wheats, who had discriminated against her for being a giant. Meliodas stopped them, then questioned Diane if she was frightened; his having treated her as he would, a normal girl of his size made her feel as though she was his size, i.e., small. Diane's encounter with Meliodas has her run straight home to tell Dolores that there was another place they could be accepted. When Diane arrived at the village, Dolores was revealed to have been killed by mountain bandits on a bodyguard job. After Diane learned that Matrona was the one who sent Dolores, she punched her in anger, upset knowing her friend would rather die, than wanting to fight.

The day after, Diane and Matrona were hired by the Knights of Liones as mercenaries to help in taking down foreign savages. This was all a ruse however, as the knights' true objective was Matrona, looking to gain reputation and prestige for taking her down. Diane and Matrona engage in battle against the traiterous Holy Knights. In the midst of the brawl, a poisonous arrow was about to hit Diane, but Matrona took the arrow in her place, severely crippling the Giant warrior chief. Despite being weakened by the arrow, Matrona used the last of her strength to take down Gannon and 330 other Holy Knights before supposedly dying. Diane mourned for Matrona's death before being captured by the Knights of Liones and arrested under false crimes. She was sentenced to capital punishment under the pretense of killing Matrona in jealousy, along with the deaths of 330 other Holy Knights to an attempt to silence all witnesses. As her punishment was read aloud, Diane was saved at the last moment by Meliodas who gained legal custody over her. Some time after this, Diane officially became a member of the Seven Deadly Sins, and became acquainted and friendly with all of the other members, including King, with whom she did not remember or recognize at all.

12 years ago
While on a mission to wipe out a group of vampires who had taken over Edinburgh castle, Diane, who was partnered with King, were suddenly weakened due to a drunken Ban's deliberate use of Snatch and as a result, the two had a hard time in battle against two Vampires, Mod and Ganne until they were saved by Gowther who had made the two vampires believe he was a part of their family and started to kill and attack one another. Diane and King were soon upset over Gowther for not coming sooner, who revealed he wanted to make it exciting.

10 years ago
The Seven Deadly Sins, including Diane, were summoned to a castle to meet the Great Holy Knight Zaratras some time after defeating the troll queen and, at the same time, destroyed the Great Druid Altar. On their way, Diane speculated that the Great Holy Knight might reward them in their last mission, though Merlin predicted that it'll be a scolding from their superior. When they find him dead, they are ambushed by all the Holy Knights in the kingdom, with Diane later being able to escape and reach the Forest of White Dreams, where she forced the indigenous Prankster Imps to hide her, lest she go on a rampage.

Introduction arc
Diane's wanted poster is displayed on a board within the Boar Hat.

Forest of White Dreams arc
The defeated Prankster Imps retreat to a sleeping Diane, inadvertently leading Meliodas, Elizabeth and Hawk to her. Diane wakes immediately upon hearing the Imps apologies for allowing a Holy Knight to come through, since they believed Meliodas to be one, and then instantly grabs Meliodas with one hand. After realizing his identity, however, she cuddles her captain, and when Elizabeth introduces herself to be traveling with him, throws a tantrum. Meliodas, after calming Diane, begins a discussion on the day the Deadly Sins were framed for the Great Holy Knight Zaratras's murder. However, he also reveals that he has almost no memories of that day, and then narrates the only memories he has, which end with someone apologizing to him, addressing him as "captain".

This leads Elizabeth to speculate the existence of a traitor, and Diane, to declare that she will help Meliodas no matter the foe. Few moments later, Hawk notices a gigantic thundercloud in the sky, from which a lightning bolt descends and immobilizes all of them, with Elizabeth introducing the assailant Holy Knight as Gilthunder. After he leads her away, ending her interruption, he expresses his desire to fight Meliodas, and reveals his connection to Zaratras, the Great Holy Knight. Before the battle, Meliodas and Diane easily break his immobilization themselves, and the former instructs the latter not to interfere. Diane quietly observes the battle, watching worriedly when Meliodas is gravely slashed. When Gilthunder continues attacking Meliodas and refuses to end the battle, Diane grabs him, and ignoring his attempts to escape her grip, flings him from the the forest. Sometime afterward, Diane leaves along with her captain, Hawk, and Elizabeth. Meliodas decides to head for Baste Dungeon, where Ban, the Fox's Sin of Greed is imprisoned, leading Elizabeth to object, citing his grave wound at Gilthunder's hands. Though he affirms her that it is not major, he soon collapses.

Baste Dungeon arc
Diane, Elizabeth and Hawk then travel to a town near the Baste, named Dalmary, in order to have the severely injured Meliodas treated by a doctor named Dr. Dana. As she sits next to Dana's house, she is watched with discriminatory wariness due to being a giant. Not long until Diane decides to head to the dungeon herself, retorting that Elizabeth would only be a hindrance when the princess asks to join. Elizabeth replies her desire to be of use, and that Meliodas was taking on "more than he can handle". This angers Diane, her saying that Meliodas was not doing so for the princess alone, and that such was his usual personality. She continues, narrating the episode of her and her captain's first meeting, and how he treated her at that time. As Elizabeth declares her wishes of wanting to have strength, Diane declares her own of wanting to be small. Abruptly, Hawk notices a huge swarm of poisonous insects flying toward Dalmary.

Although initially plagued by her fear of insects, Diane overcomes it and quickly kills them by raising huge pillars from the earth, much to the surprise of Friesia, the assailant. While Elizabeth and Hawk awe at Diane's ability, and she leaps out of Dalmary and, handing Elizabeth the duty of taking care of Meliodas, starts running toward the Baste Dungeon. Diane, later on, encounters Meliodas, Elizabeth and Hawk when the three are walking to the Baste Dungeon. She mysteriously seems to have no recollection of having defeated Friesia and having left for the dungeon previously.

Diane tries to recollect, when she suddenly finds Meliodas and Elizabeth to have vanished, and Ruin to be standing in their place. When the Holy Knight claims to have already captured them, she attacks him, but is soon revealed to be under an illusion that deludes her into seeing Ruin in Meliodas' place; she thus attacks Meliodas while believing that she is attacking the Holy Knight. Meliodas, immediately flees along with Elizabeth, and Hawk, and upon finding two civilians walking nearby, takes them along. As the five hide, Meliodas also falls under Ruin's hypnosis. Seeing Ruin in Diane's place, he, thinking he is attacking Ruin, jumps up, rolls and slashes from above, with Diane blocking it with her fist and responding by raising sharp pillars from the earth toward him, with he in response deflects. Diane and Meliodas' battle continues, uninterrupted, and only stops when Elizabeth manages to remove the source of Ruin's illusions - his staff's bell.

Later, during the aftermath of Meliodas and Ruin's battle that ends in the latter's defeat, Diane quickly defeats Friesia with a punch that utterly crushes the Holy Knight. Walking towards the heavily injured Elizabeth, Diane removes her giant backpack, intending to place her inside and take her to the town for treatment. Elizabeth, however, requests to be taken inside Baste, to which Diane complies. The second, and older shepherd is revealed to be a soldier who was ordered to act as a civilian. When he refuses to reveal Ban's location due to fear of his superiors, Diane threatens him while holding Friesia's defeated body. Inside, the group encounters Dr. Dana's daughter Sennett and Ban. As Meliodas and Ban greet each other, and arm wrestle, thus destroying the entirety of Baste, Diane simply watches as though this was a common occurrence. The group, along with Sennett and the other villagers, return to Dalmary where Diane looks after Elizabeth.

At night, during the party, Ban is formally introduced to Elizabeth; Diane has to stand while eating due to her size. During the party, Elizabeth expresses her joy, but states that the events in Baste have reminded her all the more about the Holy Knights' frightening abilities. Diane replies that while she is not interested in human kingdoms, she has no qualms with fighting for Elizabeth, since she was "really cool" that day, and did have powers: the power to move her and Meliodas' hearts. Diane also asks Elizabeth whether she could henceforth address her as merely "Elizabeth", instead of "princess", and then tells the young lady to address her as just "Diane".

Capital of the Dead arc
Diane and the others left Dalmary Town to travel on the road again to find the other Sins. Elizabeth apologizes to her for making them wait when she needed to heal but Diane said she shouldn't worry too much. As Meliodas was about to say where they should be going, they stumbled upon a suspicious group Holy Knight's who demanded to know where they were going, noticing Hawk Mama and Diane, a giant. Meliodas came out and told them that they were a traveling bar, and that Diane and Elizabeth were the attractive waitresses. The lie was working, until Diane hugged Meliodas in happiness at being called attractive and accidentally referred to him as "Captain."

When the apprentice Holy Knight was about to attack a Black Hound attacked, 'devouring' them. Meliodas scared it away by using his power and they continued their path. Meliodas told them that they are going to the Capital of the Dead to find King. When they get to a village next to the Capital of the Dead, they decide to scavenge information on how to find King and how to get to the Capital. Meliodas appointed Diane as a poster girl and Ban as a chef. Diane attempted to reel in customers, but failed as the village was isolated. The Sins then realize that Ban has disappeared and decide to go out and find him. When they find Ban, he is fighting with someone. Meliodas bumps Ban on the head and instructs him to get back to work. He and Diane then see Ban's opponent, and recognize him as King, the Grizzly Sin. Diane becomes happy and smiles at him, saying that she was happy they had found him. In response, King said nothing and floated away in the opposite direction. Diane and the others then go back to the Boar Hat, and Ban serves food to a local girl named Ellen and her brother Luigi.

They group acquired information from the two siblings on how to get to the Capital of the Dead, and were told that King had asked them previously as well. As the spoke, Diane wondered what had caused King to react in such a cold way. As they wander the village, they come across the entrance to the Capital. They are surrounded by small, light pink flowers that swirl around them until they are transported to the Capital. Ban separates from the group to find something and King follows after him. As they walk around, a Holy Knight, Guila appears, having gained access by partially killing herself. Meliodas senses how dangerous she is and orders Elizabeth and Hawk to run away to safety. Guila launches an attack that sends the two Sins flying, and Meliodas manages to catch Diane before she was impaled by a sharp crystal.

Guila then comments that the capabilities of the Giant Clan and Diane's ability, "Creation", are not very impressive. As a response, Diane demonstrates her abilities by trapping Guila using her Sand Whirl. This fails, and Guila easily frees herself with a blast from the tip of her rapier. She forces Diane back with another explosion, and Diane attempts to crush her, but is blasted again as Guila dodges it. Ban returns and attempts to battle Guila using Snatch, but she reacts by using her power Explosion. The rest try to fight Guila together but she is too powerful. Guila launches another explosion, but Diane uses her body to shelter Meliodas, leaving Ban out to be impacted by the attack.

Diane blocks all of Guila's attacks, resulting in her not wanting to move do to her injuries. King then appears to help them. Guila sends multiple attacks towards them but King easily blocks them all with his Sacred Treasure Chastiefol. Guila comments on his spear power insists on going four-on-one with the Sins. King refuses, saying he wishes to go one-on-one and would rather let the other Sins rest. Guila is caught off-guard by King's powerful magic, and is almost defeated. She attempts to give a final blow to King as he turns around, but is sent back to the living world by the force of Meliodas' Full Counter. The Sins bodies began disappearing too and they slowly return to the living world as the Capital rejects them. When they get back, they find that Guila was still in a trance of near death. King insists on petrifying her, but Meliodas offers to do something to her before they leave.

King was worried that Diane might still be injured from before and tells her to rest, but Ban laughs and tells him that she had been faking it the whole time in an attempt to get attention from the captain. King defends her and claims that Diane wouldn't do a thing like that, but unnoticed by King, Diane makes a face that suggests she was faking it. Elizabeth comments on how strong King was, which he responds by saying that any of the Sins could've beaten her with ease if they were wielding their Sacred Treasures. King is disappointed as he finds out that the other Sins no longer have them and comments on their carelessness. Diane had lost hers somehow. King chastised Meliodas and Ban for not having them, but didn't yell at Diane as she put on a puppy-eyed look. He said that her losing it wasn't her fault, and that it couldn't be helped.

Vaizel Fight Festival arc
The next day, Diane is left behind with the Boar Hat while King, Meliodas, Diane and Hawk travel to Biron, since she is easily noticeable. The next day, Diane throws a tantrum at similarly not being able to accompany them into Vaizel. Elizabeth insists on staying with Diane, and they head to look for ingredients in the nearby forest after the other Sins leave. In the woods, Elizabeth finds a mushroom-like monster, which Diane, tries to grab, considering it an ingredient. The creature, much to Diane and Elizabeth's shock, releases spores that shrink both of them. Diane wears Elizabeth's clothes and jewelry, in order for them to not be lost, and then, wanting to surprise Meliodas, enters the Vaizel Fight Festival under the name of "Matrona", with the shrunken Elizabeth hiding in the shrunken Diane's bosom.

As Matrona
The shrunken Diane is first seen during the preliminary of the fighting festival, in which, she quickly and easily defeats many of the other contenders, and advances. Afterwards, she is assigned to fight against Griamore. After she, and her opponent, have entered the ring, Love Helm, the referee, requests her to remove her cape to confirm whether she has any weapons. She does so, revealing her incredible identicalness to Elizabeth. Griamore, dismissing Veronica's worries about "Matrona" being Elizabeth, readies himself. As the battle begins, Diane immediately attacks Griamore, all of which are, negated by the Holy Knight's ability, Wall. While Diane is being pushed outside the ring, Griamore states his intentions of humiliating Meliodas next. This enrages Diane, who proceeds to destroy Griamore's ability, and then defeats him, with a single punch. This greatly surprises both Veronica and Howzer the impact causes Diane's hat to fall off.

As "Matrona" is declared the victor, her facial appearance is now revealed to be identical to Diane's, and she skips towards Meliodas, Ban and King, believing that her secret has been revealed, but is only greeted with Meliodas' question as to her identity. Irritated, Diane punches him storms off, turning back when King asks her about her body, and Elizabeth's whereabouts. Diane replies that "she" is right there, with an expression of Elizabeth's. After Elizabeth appears in Diane's bosom, Diane explains how she and the princess shrunk, upon hearing which King recognizes the creature that did so. Diane jumps over to Meliodas, merrily expressing her elation at being held by him. She then asks Meliodas to grope her as he gropes Elizabeth. When Diane becomes upset at his refusal, Meliodas comforts her, explaining that he cannot act so to an important individual as her.

Diane then watches Cain Barzad and Old Fart (King's disguise name) fight, and then, Meliodas and Ban's battle. During the latter's battle, when Meliodas appears to be weakening, Diane wonders the reason, in which King answers as being due to Ban's ability, Snatch. After Ban completely steals all of Meliodas' abilities, and stands over him, Diane yells at Ban to not further harm Meliodas. Meliodas himself refuses to give up, leading Diane to theorize that Meliodas is baiting Ban to delivering a powerful punch, and will then reflect it with Full Counter. King, however, explains of Full Counter's limits, that doing so would be impossible. After Meliodas somehow wins, Diane tells King that in midst of Ban's attack's aftermath, Meliodas' eyes suddenly became black, and that he had a strange symbol on his forehead; she states that Meliodas then crushed Ban's hand, then goes on to defeat him. Diane states that she has seen this before, and that it makes her feel uneasy. When the next battle is declared to be between "Matrona" and Howzer, Diane hurriedly hands Meliodas the shrunken Elizabeth and the princess' pendant, before leaving for the battle.

As the battle begins, Howzer informs Diane that her chest button was undone. After the minor interruption, he charges, attacking with a small tornado around his arms. Diane, while dodging, comments on the attack's danger. After much evading, Howzer, finally, proceeds to deal the final attack, but finds "Matrona" to be easily stopping him. Diane pushes him away with a single slap, adding that she had earlier commented his ability to be dangerous only because she did not want her clothes to be torn. Finally able to unleash his powers, Howzer uses another technique, which causes Diane no damage again, leading to Howzer's confirmation that she is a Deadly Sin. Not giving up, he then forms a gigantic twister, large enough to cover the entire ring. Despite his confidence of his victory, Diane increases her body's mass, and uses the increased gravitational force to defeat Howzer from above. Howzer then acknowledges his defeat and states that he is honored to have been fought seriously by Deadly Sin; he then confirms Diane's identity when King addresses her by her name.

During Cain and Meliodas' battle, when Diane wonders about the fighters' relationship, Ban instructs her to stop, citing the third law of the Deadly Sins. After the battle, the final battle of the Fight Festival, between Meliodas and Matrona is announced. Just as Diane suggests to merely act as if they are fighting, three women cheer Meliodas in an erotic manner. Diane, enraged, assumes that Meliodas' obliviousness is because he has relations with so many women that he doesn't recognize them all, and, enraged, punches him to the ground.

Diane refuses to believe Meliodas' claims that it was a misunderstanding, and exchanges a barrage of very powerful and relentless attacks. As Meliodas attacks, he wonders why she is as powerful even after shrinking. He then jumps, and tries to land the finishing blow. His punch is, however, stopped by Diane with one of her own. As she pushes Meliodas back, her size gradually returns to normal. Diane continues attacking Meliodas, but he repeatedly evades her by slipping through the cracks on the ring. When the audience expresses its dislike at the low seriousness of the battle, Meliodas declares his identity, and that he will now be taking over Vaizel. Ban and King also enter the ring, with Meliodas continuing that he will give the town a chance: he orders them all to leave Vaizel, lest be massacred by the Sins. A few moments later, several gigantic flares rain down on the town. The attackers are shown to be Guila, Jericho, and another Holy Knight; the citizens, believing that the Holy Knights have come to save them, cheer, but are quickly threatened into fleeing.

As Diane
Elizabeth then understands the Sins' actions: they acted so in order to have the civilians evacuate. Meliodas notes that their opponents are much more powerful than earlier, and instructs King, Diane and Ban to separate. Diane, acting upon her instruction, then reaches the area where Gideon was kept, but finds the weapon to not be there. As she wonders on her course of action, Howzer walks up from behind, declaring that he will be arresting her, since he believes that they are plotting to take over the kingdom again. Diane then notices a civilian trapped under the debris and runs to help, just as Marmas walks up to the two, and proceeds to use a technique that multiples gravity around Diane by ten times. Diane throws the civilian to Howzer, as the earth collapses due to her increased weight.

After being dropped into the pit, Hawk Mama appears before Howzer and Marmas, carrying Diane's original clothes and tosses them into the large opening. After Helbram successfully defeats the rampaging Meliodas with a portion Hendrickson's power, Diane appears from the hole, smashing Marmas at the same time. As Diane climbs out of the pit, Diane asks Howzer if he is surprised of her true size, but Howzer told her he was not and was glad that she's okay. Diane then ask Howzer to take Marmas and the old man and run away, which surprised Howzer. Diane then playfully asked if Howzer still wanted to capture her, but Howzer tells her that the Kingdom will be after them after they find out about Vaizel. Howzer at this point begins to grow feelings for Diane, realizing her true nature. Diane later finds her sacred treasure Gideon and heads towards where Meliodas and Helbram are fighting where she saved Meliodas before Helbram could take him away. Diane saw the defeated Meliodas and she went into a deep thought until she went furious at Helbram for what he had done to Meliodas and uses Mother Catastrophe to crash the area around her.

Helbram started to retreat due to Diane's great power and Hendrickson ordered him to escape, but Diane then forms a giant floating mountain and crushes Vaizel, possibly killing Helbram. Later when the smoke cleared up, Diane looked at the injured Meliodas which made him wake up and saw Diane, Diane then got so happy that she cuddled him. As Elizabeth was running toward the injured Meliodas, he was then punched by Ban who was angry at him for cutting him in half which made Diane upset at Ban. Diane later picked up Meliodas and was upset at him because he asked Elizabeth if she was alright, then he's happy which made Diane upset because Meliodas is not worried about her, he tried to calm her down by saying that she is always fine in which she replied she's not fine at all. Later, Diane thanked Hawk Mother for getting her clothes and headed with the rest to a new location to find the other Deadly Sins or the next Sacred Treasure.

Armor Giant arc
After the Boar Hat stopped at an unknown location, Diane found and heard Elizabeth saying she will return the kingdom back to the way it was. Diane told her that she shouldn't worry about it and she is free to use their powers since they are comrades. Diane and Elizabeth later met up with Ban and King who went to see Meliodas who were shocked to see the mountain sliced in half that was caused by Meliodas. Later, a group of kids who are role playing as the Deadly Sins, found the Boar Hat and started questioning them, Diane, who was hiding behind, thought everyone came back, and appears right in front of the kids who were shocked to see a giant, thinking that she's going to eat them which got her angry, saying she doesn't eat people.

After all things cleared up, Diane ends up playing with the kids, in joy. Pelliot then told them about a Mountain God who lives in Ordan mountain. Then they were later informed by a villager that a group of Holy Knights the Dawn Roar are up in the mountains hearing this the kids headed towards the mountain to find them. The Deadly Sins then hear from an injured knight that an "Armor Giant" was at the mountain and beaten them all with ease. Meliodas then realize it was Gowther. Once Meliodas explains the situation to Diane, the latter then realize that Gowther was pretty big and wears armor. Diane asks if she can go along, but Meliodas refuses and orders her to stay behind and protect the sick Elizabeth.

Diane was surprised but happily agrees to stay behind. Diane was later informed by Hawk that Cain Barzad came to the Boar Hat while he called him names which Diane told the latter it was rude. When Cain ran out of the bar to see what's happening in the forest, Cain was surprised to see a giant in the area and wonders how she knows him. The Deadly Sins then return with Gowther where Diane and Elizabeth were surprised to see Gowther without his armor, but all of them end up celebrating. Gowther later used his power Invasion on Diane and Ban which he revealed that Diane was lying about her true height which is 30 feet tall not 29 to much to her embarrassment, smashed him to the ground repeatedly. When Gowther revealed that Elizabeth is in love and it could be Meliodas, King and Ban try to calm Diane down but were surprised to see her pass out due to drinking.

Kingdom Infiltration arc
Diane was chatting with Hawk Mama about what she eats which Diane doesn't understand and got mad when Meliodas needed comfort from Elizabeth as she break the window. As Meliodas explain his reason to head to Liones and get his sword back, Diane wonders why the Demons aren't released yet, Meliodas reveals that there are more pieces to the Coffin of Eternal Darkness since the seal is incredibly strong and there would have been a sign. Hawk asks why the Holy Knights are after Elizabeth as well, until a mysterious Holy Knight appears and reveal that Elizabeth is the last key needed to revive the Demon Clan. The mysterious Holy Knight took Elizabeth in which Meliodas orders Diane to toss him to Liones along with Ban and Gowther. Diane grabs hold of the Deadly Sins as she told Meliodas to bring back Elizabeth, and toss them toward Liones in full speed.

Diane and King start traveling towards Liones by foot along with Hawk Mama, planning to help out as they are the only one's possessing their Sacred Treasure. She asks King if he had ever seen Meliodas so angry before and King replies that it was his first time seeing him like that. Diane starts wondering if she wash the one kidnapped instead of Elizabeth, would Meliodas be as angry as he did with Elizabeth. King tells her that Meliodas will definitely go to save her since they are important friends, and states that he himself will definitely come for her. Diane tells him that she is happy, but King wonders if she actually cheered up. He soon realizes that they should hurry and summon his pet, Oslo. He reveals its ability of teleportation and tells Diane to enter Oslo's mouth. They eventually realize that she is too big for the Black Hound's mouth, so Diane tells him to push her in. King blushes at the sight of her rear end and quickly orders Oslow to open his mouth wider.

Diane arrives at Hendrickson's Magical Research Facility, and is immediately questioned by Dreyfus, asking for her goal. Without hesitating, the Deadly Sin demands to have Elizabeth returned, leaving the Great Holy Knight only confused. Howzer becomes more and more nervous, and Jericho decides to deliver the first attack. Diane straightaway swings Gideon, destroying part of the building and blasting Jericho away. Gilthunder then proceeds to begin attacking, and under Dreyfus' commands, Howzer reluctantly enters the battle as well. However, despite using a combined technique, Diane was able to fend off the technique by using Ground Gladius. When she attempts to unleash Ground Gladius for a second time, Dreyfus easily blocks it and uses his ability Break to pierce through her chest.

After being heavily damaged by Dreyfus' Break ability, Diane briefly collapses on the floor whilst coughing out blood. Helbram returns to the group of Holy Knights after evading Diane's Ground Gladius by sacrificing some of his subordinates. Diane attempts to move again, but Dreyfus uses Pierce to damages her leg, and is sent flying away to the city by the Great Holy Knight's technique, Pulverize. When she crashes into the buildings and astonishes the civilians, Dreyfus proceeds to use an Incantation Orb to project his voice throughout the kingdom, stating that the Seven Deadly Sins have infiltrated Liones to stage an attack. The civilians begin attacking and throwing rocks at the confused Diane who tries to explain what's happening to the people. Helbram proceeds to destroy more buildings to frame Diane as a villain. Guila notices the trickery and demands Helbram to explain his actions, which he replies by saying that the Sins will play the role of villains so that the Holy Knights can be heroes. Suddenly, Zeal notices Guila, when a building starts collapsing above. Without thinking, Diane leaps and dives forward to protect Zeal, causing herself to be completely immobilized by the collapsed building. As the Holy Knights prepare to kill her, Howzer and Guila steps in to protect Diane.

As Guila and Howzer initiated a suicidal battle against their former comrades, Diane tells Zeal to stay down while she protects him from the destruction caused by the two rogue Holy Knights' Combined Technique: Bomb Cyclone. As Dreyfus and Gilthunder fled the battle field due to Dreyfus' injury. Helbram was left behind to finish them off which he called upon Call of Inferno which nearly killed Howzer and Guila until Diane stood up and smash Helbram before he could do anymore damage. Diane gave Zeal back to Guila and told them to get to safety, but Howzer refuses, saying that she should worry about herself more than others for once in which she smiled. But Helbram raised up and striked Diane with Killer Iceberg that heavily damaged Diane even further and put her to a near death situation. Helbram unleashes a barrage of ice attacks to finish her off when suddenly King appears and saves Diane. As King tries to find the one who injured Diane, Diane told King it wasn't Guila or Howzer as they are the one trying to protect her until she passed out.

As King protected her from Helbram roots attack, Diane woke up for a moment and says that she remembers this smell and says King's true name, Harlequin as she shed tears. After Helbram was killed by King, King flew towards the injured Diane and apologized to her for getting her in trouble, but Diane instead thanks him for saving her. King told Diane to leave everything to him, but Diane then said Harlequin which surprise King until Diane said that the name sounds nostalgic to her, but doesn't know why. King smiles and said it could have just been a dream. Diane later starts forcefully getting up while King tries to convince her to rest due to her injuries, but Diane refuses as Elizabeth needs to be saved and said that he doesn't need to worry because he already healed her of her wounds. While the others were trying to get Dreyfus on their side to save Elizabeth, Diane told Dreyfus she did not care if Dreyfus hurt her, but wanted to save Elizabeth as she was a important friend to her. As everyone got ready, they headed out to Hendrickson's location to save Elizabeth.

While on their way to save Elizabeth, Diane and the Sins feel a large amount of power exerted with very strong force in a nearby battle. After Gowther explains that Meliodas is fighting three Great Holy Knights, Diane begs King to go and help Meliodas, but King refuses as he wants to remains near Diane since she is still injured and knows that Meliodas is fine on his own. As everyone senses Gilthunder's full power, King realizes the fighting has stopped. Diane screams, thinking that Meliodas was killed, but Gilthunder, Margaret and Meliodas show up, revealed to be fine. Diane begins to cry and holds Meliodas, which Meliodas ignores and tells the group that they need to rescue Elizabeth. The group heads to the castle to rescue Bartra Liones and Elizabeth, but are teleported to a forest Vivian. Fortunately, they are sent back to Liones by a mysterious cloaked figure, who is soon revealed to be Merlin of the Seven Deadly Sins. After Merlin freed Elizabeth and Bartra. Elizabeth was worried over Diane's wounds when Diane revealed that she was saved by King Elizabeth felt glad that she was fine. Meliodas pointed out that they have defeated Hendrickson and freed the king, and ask Dreyfus what would he do now. As Dreyfus admitted defeated and was crying to know Griamore is alive, Meliodas happily declare that everything was fixed. However, after Merlin, Arthur and Barta left to treat the kings wound, the castle was attacked by Hendrickson and awakened all of the New Generation's demon blood.

As Jericho transforms into Demon and was about to kill the slowly transforming Guila and her brother Gustaf, Gowther along with Diane appeared and stopped Jericho from killing. Gowther used Invasion on Jericho and Guila to try and keep them calm. Diane was shocked and disgusted with Hendrickson who revealed that he used Enslavement of the Dead to revive Helbram and used him as a slave to fight off King. Seeing Elizabeth taken away by Hendrickson, Diane pleads her friend not to go while distracted it allowed Jericho to strike back and injure Diane again. As Diane was fighting off Jericho, she over heard Jericho saying that she want to be stronger then her brother which made Diane believe that Jericho is still alive inside, but doesn't know what to do. As Diane refuses to kill Jericho, Ban appeared and removed a strange "plant" from Jericho which cured her and returned back to normal. Diane was amazed at Ban's skill while she told Ban and King to go and cure the Hybrid Demon while Diane and the others go to save Elizabeth and help Meliodas.

Diane appeared at Merlin's Old Castle while destroying Hendrickson's severed arm while at the same time, saved Hawk and the bleeding Elizabeth which Diane claim that she will not forgive Hendrickson for what he did to Elizabeth. Later, Diane and the remaining Deadly Sins appeared to face Hendrickson in a final battle. As Hendrickson taunts the Deadly Sins for being out numbered due to the New Generation transforming into Demons, Meliodas points out that he should check again. Hendrickson senses that all of the New Generations were stopped as they return back to normal due to Ban and King's help while the other Holy Knight are currently surrounding the ruin castle. Hendrickson, however, was joyful to admit that the situation became more interesting and wondered how the Deadly Sins defeated the New Generation so fast, but admitted that the Sins can't defeat him. As the battle went with the Deadly Sins working together to fight against Hendrickson, the latter admits that he is invisible due to the demonic power, but when Diane traps him with Double Hammer, Meliodas explains to Hendrickson that demonic powers can heal wounds, but if he is not immortal or something, it would have been pointless as the damage would still remain. Hendrickson then smashes Ban into a wall where he found the demon corpse and returns to Hendrickson, questioning him on where he found it and why does he have it. Then the wall breaks down to reveal the demon which shocks the Deadly Sins.

Diane was shock and disgusted by the demon, but when Ban slam Hendrickson into the floor, Diane was left behind due to her size while the other Deadly Sins follow Hendrickson. When Hendrickson took the Gray Demon blood, Diane along with the other Deadly Sins were blasted out of Merlin's Old Castle, while passing out. Diane, however, was awake and used Rising Meteor on Hendrickson, sending him up towards the sky because of the rising ground. Diane told King to finish him which King did by almost using Form Eight until Hendrickson used Dark Nebula which easily defeated King and Diane. Diane watches in tears as Hawk died while protecting Elizabeth and Meliodas. When Elizabeth unlocks her hidden power and healed everyone, Meliodas thought of a plan and ask Gowther to use his ability to spread the message, but King was in tears, trying to reveal to Meliodas that Gowther was killed as his head was chopped off, but to Diane and King's horror and shock, Gowther was fine as he was searching for his glasses while holding his head. Once Gowther spread the message through Broadcast, King along with the other Deadly Sins attack Meliodas and Hendrickson with all of their powers, however, Diane was in tears for attacking Meliodas. It was revealed that Meliodas is charging up for Revenge Counter as it is Meliodas ultimate technique in which he finally killed Hendrickson, ending his reign. Diane watches in sadness as Elizabeth was taking care of Meliodas wound, feeling insecure about herself again. Once Bartra returned from Camelot with Merlin by his side, he forgave the Holy Knights and cleared the Deadly Sins name for their crimes. As the others started to grieve over Hawk's death, the black matter on the pig's dead body started to disappear and revealed that Hawk is still alive, but shrunken. However, everyone was still joyful for their friend being alive.

Post-Kingdom Infiltration arc
As Liones was being rebuilt, King ended up being trap under a column due to helping an old man, Diane appeared in regular human size as she lifted the column with ease and surprised everyone. King was shocked to see Diane in regular size and in different clothes, but revealed that Merlin offered her magical pills called Minimum Tablets that allowed her to shrink for seven hours as her clothes are being repaired. King continued to stare at Diane which made her ask King if she looks strange in western clothes or being small in general. King, however, revealed that he doesn't care if Diane is big or small, she is still Diane which made her smile. King asks Diane if she could invite Meliodas to the National Foundation Festival despite calling himself stupid in his head as he wanted to ask Diane, to his shock, Diane asks King out instead. The next day, Diane wore the new outfit Merlin made her which she told the latter she loved it, despite having a hard time to choose between the two she made which confuse the mage as she didn't make two. Diane grew greatly upset when Ban didn't wear his new outfit as Diane and King picked it out for him while being rude about the outfit as he didn't care enough to notice it.

During the National Foundation Festival, Diane in her regular size serves food and ale to the patrons of the Boar Hat in celebration from night to dawn. Later back in her true size, Diane attends the award bestowment ceremony with the rest of her fellow Sins with the exception of Ban and King who left for the new Fairy King's Forest and Escanor still missing. When the king decides to go on with the ceremony without the missing three, Diane and her fellow Sins were surprised of Meliodas' sudden objection due to some Holy Knights talking behind his back, revealing to be three members of the Pleiades of the Azure Sky: Deathpierce, Dogedo, and Waillo. Witnessing Dogedo challenging Meliodas, Diane and the others were confident that it's obviously their captain's win as the Dragon's Sin of Wrath defeated the Platinum-ranked Holy Knight easily. The Serpent's Sin of Envy remains clueless to Hawk's sudden breakdown of his inflated ego after the talking pig read her Power Level through Balor's Magical Eye After the issue settled and the ceremony over, Diane accompanies the group heading to the castle in meeting with the king before running into Gilthunder, Howzer, and Griamore. At the throne room, the Serpent's Sin of Envy was slightly disturbed when Bartra informs them of the omen of the Holy War still growing and a growing threat in the south of Britannia, Camelot. Outside of the castle, Diane discusses with the group before experiencing a sudden earthquake unaware of the Demon Clan's revival and notices Meliodas' expression changed into an angered look with sweats dropping in fear.

Albion arc
Having regained her lost memories at some point, Diane switched to human size and searched around the capital looking for King only to bump into Elizabeth in her new clothes. Escorting the princess to the Boar Hat, Diane expresses her frustration of King not being there with her and later on supports Elizabeth's love for Meliodas after revealing that she now remembers her past with King as she cries in tears. Later, Diane came crashing into Merlin house in tears, begging Merlin to find King while Elizabeth try to calm her down and Merlin tease saying he might have turn invisible. Merlin than told Diane that if she stop thinking about him, he might pop up and told her that they should get ready for Camelot soon. As the two girls left the house, Diane spot Meliodas and ask Elizabeth to confess, but the princess left in embarrassment while Diane chase her.

While cheering Elizabeth, the two waitress came across a confused and puzzled Zeal who doesn't even remember who he is. Diane spot Guila and Gowther who quickly rush over them to help Zeal, but Guila doesn't even remember who her little brother is. A confrontation with Gowther soon after reveals that Gowther had manipulated both sibling's memories; Guila's memory manipulation occurring during the battle between Ban and Meliodas. It is during that battle, Gowther had noticed that both Ban and Meliodas (who despite suffering heavy injuries), increased in power level. After coming to the conclusion that feelings of love are what caused this change, Gowther switches from studying friendship, to love, using Guila as his makeshift lover. Gowther attempts to convince Diane that the memory manipulation was necessary, as it is what helped suppress the Demon Blood within Guila at the time. Revealing that he has made Guila's memories a much happier one, Gowther asks Diane and Elizabeth which set of memories Guila would be happier with. Diane disagrees with this, asking Elizabeth to go get Meliodas and Merlin. Gowther attempts to stop Elizabeth, but is stopped by Diane. Here, the battle between the Sin of Lust and Sin of Envy begins.

Soon, Diane came out victorious after defeating Gowther while still suffered some injuries while telling Elizabeth to look after Guila and Zeal while Gowther sulk in his defeat. After Meliodas commands Gowther to restore Guila and Zeal memories Guila then apologizes to her unconscious brother for how she treated him.Diane then observed as Merlin used her Absolute Cancel on Gowther she was then surprised to see her teammate was actually a Doll. Diane was later taken to Camelot along with the others to stop a Albion from destroying the kingdom. After Meliodas destroyed the Demon, another Demon appeared who happened to be Galand of the Ten Commandments. While Galand has a hold of Meliodas in their battle, Diane takes revenge as Merlin brings her back to her original size and transport her Gideon. However, Galand kicked it towards her head causing her to go out of commission.

Istar arc
Later she began to gradually lose her memories about the Seven Deadly Sins, because of Gowther's powers, Lost World. As she finally forgot about the whole time spent with her comrades, she leaves Camelot to come back to her hometown, Megadozer. On her way to the homeland of the Giant Clan she meets again Galand along with Monspeet, another one of the Ten Commandments. As her situation seems desperate, she is unexpectedly saved by Matrona and the two manage to escape from the two demons.

Great Fight Festival arc
Sometime later, Diane is shown watching Matrona dancing. Upon pointing out that dancing looks more fun than fighting, Diane is surprised to hear Matrona state that her fighting days are over and that she would become a dancer. Diane begins dancing, but Matrona considers it terrible much to the Deadly Sin's disappointment, scolding the kids who playfully make fun of her, but quickly changes her attitude when Matrona talks about Zalpa. She explains that it was her kindness in sparring Zalpa that lead to her own survival and thanks Diane for it.

Matrona mentions the Ten Commandments and instinctively Diane falls to the ground, remembering her experience with them. After some encouragement from Matrona, she aggregates her courage and decides to try dancing once more. Matrona then explains the concept of Drole's Dance and the legend surrounding it which fascinates Diane, despite being confused by the explanation. However, she decides to practice by herself, where she begins questioning her memory loss and the changes that have been made. Her reminiscing is cut short when she experiences a similar fear to that of the ten commandments. She notes the presence is weaker as a Blue Demon passes by her, and proceeds to examine the pamphlets it was carrying.

After Zalpa's children Sol and Della injured and can't be healed again, Matrona decides to head and join the Vaizel Fight Festival to find a way to heal Sol and Della. Diane follows Matrona and brings her Gideon after Zalpa ordered her.

Arriving at Vaizel, Diane and Matrona discovered that the whole city turned into a giant maze. In order to reach the tournament place, both of them must pass into the center. Diane and Matrona try to cheat by destroying the maze wall and jumped through the maze but failed as the wall keep generating, proving that the maze was created by someone. Somehow, Diane got separated from Matrona and encountered Elizabeth and Hawk who also got separated from Meliodas and the others.

Due to her memory loss Diane shows her hostility to Elizabeth due to being a human and refused her help. However, Diane prevent Elizabeth's death from falling into a gap and in return, Elizabeth effortlessly removes giant leeches that attack Diane, making her start to believe Elizabeth's claim that they are actually friends and know each other.

Diane, Elizabeth, and Hawk were ambushed by multiple fake Meliodas who later revealed as Prankster Imps and immediately saved by Gilthunder and Howzer who also participated in the festival with the other from Boar Hat. Diane who still losts her memory doesn't recognize them, even one of her Seven Deadly Sins comrade, King.Later, an Earth Crawler appeared and attack them. Diane requested Hawk to be on Elizabeth's side while she, Gilthunder, and Howzer performing a team attack to defeat the monster.Just when the three cheers, the Earth Crawler begin to counterattack, making Diane, Gilthunder, and Howzer cornered. However, Gilfrost, a participant of the festival come to their aid and easily defeat the crawler.

Memories of the Holy War arc
After Meliodas death at the hands of the Ten Commandments, Diane and King take refuge in the Fairy King Forest. One month later, with her memories still lost, Drole and Gloxinia resurface, abducting them and is easily defeated by the former Giant King. After which Diane and King are healed and offered the chance to be trained by their predecessors.

Diane is then sent with King back to the past during the Holy War, and finds herself in the body of Drole 3000 years ago, along with discovering that Drole fought with Meliodas, Gloxinia, and Elizabeth. During which, they easily push back a demon advance, even defeating one of the Ten Commandments, Calmadios. Soon afterwards, the demons start moving towards the headquarters of Stigma, the Fairy King Forest, and Diane leaves with King to support Meliodas.

After watching Elizabeth defeat two of the Ten Commandments, Diane notices a loss of magical power from the Forest, and while rushing their, runs into Gowther, who reveals that he is a puppet created by the real member 500 years ago when he was imprisoned. King then decides to rush to the Forest, while Diane stays behind to talk to Gowther about ending the War.

However, their conversation was cut short by Zeldris appearing. Diane told Gowther to run while she held him off, but was defeated by a single kick. Zeldris then offered her (as Drole), the choice to either die, or join the Ten Commandments, and even referenced a life of isolation and violence Drole despised, something Diane found very familiar. Instead of choosing, though, she ran for it.

This choice to run was deviant enough from the past that she came back to the present, and after telling everyone her choice, kissed King.

Current arc
After passing their trials, Diane, along with King, finally reunite with the Seven Deadly Sins through Oslo's portal. Diane tells to the other sins how happy she is to see them again, wishing that the captain were still alive. When she realizes that she landed right on top of Meliodas, she is shocked at first to see him but quickly get happy to see that he is alive.

Meliodas tells Diane that there is something different about her, to what she replies she simply got her lost memories back, much to Gowther's surprise which claims that is impossible to restore purged memories. Diane says that he is wrong, that precious memories never dissapears. Then she declares that she is gonna to help him to reclaim his "heart" so she could keep the promise she made 3000 years ago. King Bartra explains the situation and shows Gowther the heart he once had, causing him to remember scenes from his past. Gowther then suddenly runs off. Diane asks Merlin for one of her pill to shrink to human size and goes to chase after Gowther with the other sins.

As Gowther is about to purge all of his memories, Diane stop him with a drop kick. When Diane confronts him about his heart, Gowther tells her to not interfere and tries to hit her with energy arrows, but Diane effortlessly dodges all of them. Gowther is shocked when he realizes that Diane power level rises as she was dodging his attacks, revealing her power level to be 15,100. Diane claims she could easily keep dancing and make it higher but she doesn't want to fight him and she just wants to help him. Calculating his chances of winning as low, Gowther tries to escape, but King block his way. He then tries to use Lady Veronica as a hostage but due to her resemblance to Nadia but he can't do it, so he tries to purge his memories once again but Diane quickly stops him.

Merlin appears and explains the reason behind Gowther's behaviour. Diane gives words of encouragement to Gowther. These words reach Gowther, who regain his original magic power thanks to that, and heartfully thanks Diane.

Days later, Diane along with Elizabeth visits Elaine to see if she is doing well. While they are chatting, Diane suddenly remembers that she saw a person who was an Elizabeth look-alike, and tells her.

Later, the Sins have a celebration in the fixed Boar Hat and drink. During the celebration, the Captain drinks a barrel of alcohol and she tells him to chug. After talking about how their allies have grown and how they're all together again, Diane does a toast with the other Sins. Then she asks Gowther how did the Gowther (the demon) end the holy war, however Gowther couldn't say anything yet and Diane apologizes for putting him in a tough position. As Merlin points out that Zeldris is still out there and that his power is unknown, Diane tells them that the Demon King lent power to Zeldris and is his representative. The discussion ends with Meliodas telling them that freeing people of the commandment and liberating Camelot is top priority right now.

After Elizabeth told Diane and Elaine what Zeldris told her, Diane becomes shocked that she was the Elizabeth from their training. Diane tells her that it was rude of the captain to brush off the conversation with Elizabeth. Diane then tells Elizabeth that she will help her get her memories back and is cheering for her.

A while after their conversation, Diane hold back Elizabeth, who is telling her that she needs to let Meliodas know about Barzad being bitten by a werefox. After Elizabeth faints, Diane thinks that the curse moved to Elizabeth, only to be corrected by Meliodas saying that her memories are returning. Diane happily tells King about how Elizabeth was the reincarnation of the Elizabeth 3,000 years ago. She is then silenced by Merlin but continues to say that Meliodas was being mean for not answering Elizabeth's question. Diane and the others become shocked when Meliodas tells them that Elizabeth will die in three days.

Diane starts crying when Meliodas explained the curses that he and Elizabeth have. She asks him what will happen when the curse is broken. Meliodas responds that his eternal life and her perpetual reincarnation will stop. Meliodas reminds Diane of what they have to do right now.

Abilities and Equipment
As a member of the Seven Deadly Sins, Diane is shown to be incredibly strong. She was able to punch the ground and use it to stop a horde of bugs from destroying a town. She has also shown to have great endurance as she was able to resist Gilthunder's lightning and even break free from it. As Matrona (normal human size), she possesses incredible physical strength and speed which she displayed during the fighting festival's preliminaries by defeating more than ten men quickly and with ease. Even as a young child, Diane demonstrates an extraordinary connection with nature, being able to create two Golems. Matrona, who trained her all her life, said that Diane had the potential to become the strongest warrior of the entire Giant Clan.

After passing the trial, her connection to the earth increased to where she can increase her power farther while dancing.According to Melascula, her strength became comparable to Drole's. Drole himself believed that eventually she will become a greater ruler of the Giant Clan than himself because her love made her stronger than mere combat power.

Immense Strength: Since she's a giant, Diane is able to perform staggering feats of strength, able to clash with the likes of Meliodas in terms of strength and even break through barriers capable of withstanding meteors with a single punch. She can swing a war hammer with a weight of 998 kg (2200 Pounds).

Enhanced Speed: Using her strength, Diane is actually incredibly fast and agile, however due to her giant size this speed is reduced to nil, but when shrunken to human size her speed increases and is able to dodge rapid arrows shot by a foe of similar ability such as Gowther.

Immense Endurance: Due to being a giant, Diane is able to withstand several mortal blows, such as being pierced through the shoulder and thigh and still move fast enough to save citizens from collapsing buildings, and still retain consciousness even after losing blood and taking a further beating.

Enhanced Durability: Being a giant, few attacks are powerful enough to actually cause grievous harm to Diane and she can shrug all but the most powerful attacks off powerful Holy Knights.

Abilities

 * This ability, which is exclusive to members of the Giant Clan who have a deep connection with nature, enables Diane to manipulate the earth.

Weapon

 * Gideon: Diane's sacred treasure; Gideon, is a war hammer designed for the Giants' Clan. It is made of material that is stronger than steel and weighs approximately 2200 pounds. It is able to draw out the full capability of her ability, Creation.

Power Level
In her human size, Gowther assessed her strength level to be at 950.

After passing the trial, her power levels are as follows:

Performing Drole's Dance, her power levels are as follow:

Meliodas
Diane and Meliodas are both members of the Seven Deadly Sins. She was in love with Meliodas for treating her like a normal size girl, so much that she immediately desired to fornicate with him after shrinking in size. She often gets very jealous of other girls who she suspects of having a close relationship with the captain and deals with it by raging at him. Her future dream was to become little and have children with Meliodas. She respects him a lot and calls him captain. However, her feelings of love toward Meliodas disappeared as she regained her memories of King, thus falling in love with the fairy. She still shows respect and care for Meliodas afterwards.

Ban
Diane and Ban are both members of the Seven Deadly Sins. They are generally friendly with each other and are shown to have a teasing relationship. They tend show a bit of rudeness to each other when they converse. They are shown to have strength rivalries by arm wrestling, which Diane is shown winning by using only a finger. Despite their rivalry, Diane is shown to care for Ban, getting upset when he didn't wear the new outfit she and King bought for him. Ban is aware of Diane's abilities and is shown to worry twice over her raging.

King
Diane and King are both members of the Seven Deadly Sins. When she encountered him after ten years, she was shown to be happy to see him and didn't appear to be aware of King's love for her. When Diane was a child, she spent five hundred years playing and forming a deep friendship with King after she had rescued his unconscious body from a river. While playing a game, King promises to grant Diane a wish if she could catch him. After winning, Diane asks King if he loves her. After saying yes, Diane asks him to love her forever, to which he agrees. However, King begins to regain his memories and has to go back to his home. He breaks his promise of not leaving her after he doesn't come back, leading to her memories of her time with him being erased. After King saved her from Helbram, Diane began to regain her memories of their past and her love for Meliodas was replaced with King. When King went missing, Diane grew upset and began to cry, as she wanted to tell him how she feels. She claimed that she would die of loneliness if he were gone. It is believe that Diane still loved King even when her memories were erased, but she could not recall King at the time and loved Meliodas in King's place. Eventually when Diane's memories returned, her and King kiss and they become a couple.

Gowther
Diane and Gowther are both members of the Seven Deadly Sins. They are fairly friendly with each other. There was an instance where Gowther revealed her true height to the other Sins and she grew very upset at him, calling him a jerk. After finding out Gowther erased Guila and Zeal's memories of each other, Diane became furious and battled the Goat sin. Gowther erased Diane's memories using Lost World. When she regained her memories and returned to the other sins, Gowther began regaining his own. When he tried to use Lost World on himself out of fear for the new feelings, Diane stopped him and encouraged him to let them come. Diane comforted Gowther and he thanked her for helping him choose the right path. The two now appear as good friends. During her flashback as Dolor, she met Gowther of 3,000 years ago. As Gowther left Dolor (Diane) to fight a demon, he tells her "Until we meet again." When Gowther regains his memories, Diane repeats this, recalling how they have met again.

Merlin
Diane and Merlin are both members of the Seven Deadly Sins. Diane seems to like Merlin and has a good relationship toward her as she was displeased when Merlin didn't rejoin the Deadly Sins. Diane holds Merlin very highly, seeing her as a genius due to creating a pill that will shrink her for seven hours. They are on good enough terms that Merlin is more than willing to use her magic to shrink Diane to human size whenever it is necessary, and she even made new clothes for Diane as well. Merlin was the only one who she depended on to find King after he went missing for days.

Escanor
Diane and Escanor are both members of the Seven Deadly Sins. Despite being teammates, Diane was shown to be weary of Escanor when he was at his prime, and would rather not make an enemy of him.

Elizabeth Liones
At the beginning, Diane disliked Elizabeth as she was jealous of her close relationship with Meliodas. She also envied her small stature and her abilities to be able to take care of Meliodas when he was sick or injured. However, after seeing how courageous Elizabeth was when she sacrificed herself for innocent citizens, they developed a closer relationship and Diane acknowledges her, even stating that she doesn't mind fighting for her. Diane later grew to care for Elizabeth as a dear friend, as she was worried about her when she was kidnapped. Diane also supported Elizabeth's love for Meliodas after regaining her love for King.

Bartra Liones
Not much is known about Diane and Bartra, but Bartra seems to trust Diane like any other Deadly Sin.

Howzer
Diane met Howzer during Vaizel Fighting Festival while disguised as Matrona in a human-sized stature. After knocking him out in their battle, Diane apologizes and shows remorse for having hurt him. Howzer then develops feelings for Diane and they form a friendship. Howzer protects Diane after she is severely injured by Dreyfus and Helbram. Gowther assessed that the only reason Howzer had been with the Deadly Sins was because of Diane, and he appeared to be happy when Diane completely lost her memories of King, thinking that the rivalry for her attention with King wouldn't exist anymore.

Dreyfus
Despite Dreyfus heavily injuring her and almost killing her, Diane still asks Dreyfus to help rescue Elizabeth and doesn't seem to hold a grudge against him.

Guila
Diane and Guila were enemies and battled each other while in the Necropolis. However, when Guila realized that a heavily injured Diane was being framed by Dreyfus, she regretted the way she had treated her. These feelings were strengthened when Diane protected her younger brother, Zeal, from a falling building. This caused Guila to instead fight for Diane, protecting her from the Grand Masters alongside Howzer.

Matrona
Matrona was once Diane and Dolores' teacher who trained them into becoming strong Giant warriors. Despite Matrona being Diane's legal guardian, Diane disliked Matrona's warrior life and her lack of empathy. Diane and Dolores wanted to have a peaceful life and not fight in battles, but Matrona refused to accept this. Despite her dislike for Matrona, Diane greatly respected her for her bravery and loyalty to her Giant Clan, and greatly mourned Matrona's supposed death. Diane respected her enough to use her name as her alias during the vaizel fighting festival. After learning she was still alive, fighting along side her once again, and even meeting her new family, the two have since buried the hatchet, and have finally learned to accept one another.

Dolores
Dolores was a close friend of Diane during her time at the Giant Clan. The two share a love for a peaceful life outside of the Giant Warriors, but Dolores was too meek and timid to do anything about and was sadly killed at battle.

Drole
As the former king of the Giants and as member of the Demon Clan's Ten Commandments, Diane viewed Drole as a powerful enemy. During the Great fighting festival arc, Diane was visibly shocked by Drole's abilities and combat skills, as they both outmatched and canceled out her own. After being confronted by him and the former fairy king, Gloxinia in the forest, Diane was more than prepared to fight them alongside King, which impressed Drole. When they revealed their intention to betray their comrades, and then later when the two ancient kings send her and king to the past as part of their trial, Diane learned much about Drole, the holy war, and the events that lead to them joining the Ten Commandments. After passing the trial and regaining her memories, Diane began to view Drole as an ally, and even seemed to have newfound respect for him. Drole in turn showed even greater respect towards Diane for how she passed her trial, believing that eventually she could be the next ruler of the Giant Clan. During his final fight with Chandler, he helped her escape, and told Diane how kind she is, and how that kindness would make her a better ruler of the Giant Clan than he ever was, stating that he would gladly become the shield for the future "Giant Queen".

Side Story 3

 * Diane & Matrona vs. Gannon & Holy Knights: Tie

Vampires of Edinburgh

 * Diane, King, & Gowther vs. Mod & Ganne: Win

Baste Dungeon Arc

 * Diane vs. Friesia: Win
 * Meliodas vs. Diane: Indecisive

Capital of the Dead Arc

 * Meliodas, Diane & Ban vs. Guila: Indecisive

Vaizel Fight Festival arc

 * Griamore vs. Matrona (Diane): Win
 * Matrona (Diane) vs. Howzer: Win
 * Meliodafu vs. Matrona (Diane): Draw, interrupted
 * Diane vs. Helbram: Win

Kingdom Infiltration arc

 * Diane vs. Dreyfus, Gilthunder, Howzer, & Helbram: Lose
 * Meliodas, Diane, Ban, King & Gowther vs. Hendrickson: Lose

Albion arc

 * Diane vs. Gowther: Indecisive
 * Meliodas, Diane, Merlin, Slader & the Holy Knights of Camelot vs. Galand: Lose

Great Fight Festival arc

 * Diane, Gilthunder, Howzer & Gilfrost vs. Earth Crawler: Win
 * Diane & King vs. Drole Golem & Gloxinia Servant: Win

Memories of the Holy War arc

 * Diane & King vs. Drole & Gloxinia: Lose
 * Meliodas, Diane & King vs. Calmadios: Win

Corand arc

 * Seven Deadly Sins vs. Melascula: Win

Current arc

 * Seven Deadly Sins vs. Chandler: Indecisive

Trivia

 * Diane is a very common given name, and the Roman name of the Ancient Greek deity, Artemis. In Arthurian legend, Diane is possibly related to Diana of the Wood due to her strong connection to nature.
 * According to the databook(s):
 * Diane's special skill is defense
 * She has no hobby
 * Her daily routine is being energetic
 * Weak Point: Bugs
 * Birthplace: Megadozer
 * What she likes about herself: Her eyes
 * Dream/Hope: Become the giant clan’s best dancer
 * Regrets: That she only ever fought with Matrona
 * The most embarrassing thing in her life: Was there something?
 * What she wants the most right now: Her lost memories
 * Favorite animal: Cows, pigs, sheep
 * Favorite smell: Green and flowers (King too)
 * Her favorite food is pork
 * Her charm points are her pig tails
 * Her complex is her height
 * The person she respects the most is Matrona
 * A person she doesn't want to make a enemy of is Escanor.
 * Diane is entomophobic, i.e., has a fear of insects.
 * Diane told everyone that she is 29 feet tall, but Gowther pointed out that she is actually 30 feet in height.
 * Due to her immense physical size, Diane is unable to sleep inside the Boar Hat, so she sleeps outside. Though in recent chapters, she can sleep in the bar.
 * Diane tends to cover her face with her hair whenever she is embarrassed or shy.
 * Nakaba Suzuki mentions that Diane's age in terms of human years would be slightly younger than Elizabeth.
 * The Sin of Envy is usually symbolized with a Dog and the color green.
 * In the Nanatsu no Taizai Popularity Poll, Diane was 5th place for postcards (217 votes), but 7th place (3781 votes) including online votes.
 * She made a cameo appearance in episode 9 of Saenai Kanojo no Sodatekata.
 * According to Meliodas, her measurements (in her shrunken form) are: 91-58-90 (36-23-35).

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Diane