Diane

is a member of the Seven Deadly Sins, titled the Sin of Envy, with the symbol of the Serpent. She is a member of the Giant's Clan, and is thus much larger than ordinary humans, including her fellow Deadly Sins. However, Diane left or was separated from the Giant's Clan when she was a child for unknown reasons.

Appearance
As a giant, Diane is several times larger than an ordinary human being. She is a fair maiden, with pink eyes and medium length brown hair which is tied up into large twin tails. She has a particularly well-developed and curvaceous body. Like most of the other Deadly Sins, her facial appearance is relatively childlike and has shown little change over the years. Her attire consists 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 studs; her right one was destroyed by Gilthunder during the fight in the Forest of White Dreams and it has not yet been replaced. She also wears backpack previously used by Meliodas.

Ten years ago, Diane wore full body orange armor with a unique helmet like the rest of her fellow Deadly Sins. Her symbol, which is of the Serpent, is located on her left outer thigh. Diane's wanted poster depicts her with light colored hair. When she was still a child, she wore ragged clothing until King made her a new set. Her current clothes resembles what King made for her, having sewed it herself by using leather derived from Dusk Bison skin.

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 to display the same, and becomes very delighted at 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.

Due to her size, she cannot help Meliodas in any way other than fight for him, she has expressed her strong desires to be smaller, contrary to Elizabeth's desires of being strong. Like Elizabeth, Diane does not mind when Meliodas does something perverted to her, but gets angry and jealous if he does it to others. Despite Diane stating that she has no interest in humans, she still selflessly saves people who are in danger - when the elderly man in Byzel and Zeal were at risk, Diane risked her life to protect.

Despite her brave and strong appearance, Diane is a somewhat emotionally fragile person, as displayed for her hatred of loneliness. This was shown when she was a child when was waiting in tears for King to return for her and insisted him to stay by her side when she was sick, instead of getting herbs to heal her. Diane possesses the same kind of feelings toward Elizabeth after she had been kidnapped by Helbram, wanting her back to not feel alone again.

History
Many years ago, after Diane had left or was separated from the Giant's Clan, 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 hunter had a grand child now. Years had passed by without King or Diana noticing. 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.

After hundreds of years later, Diane had grown into a woman, and 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. At some point of time, Diane joined the Seven Deadly Sins, though precisely why hasn't been revealed yet. In a mission to wipe out a group of vampires, Diane and King were suddenly weakened due to a drunken Ban's deliberate use of Snatch and as a result, the two have had a hard time in battle. Diane did not know of the cause until 10 years later when Gowther revealed that event. Before the betrayal, Diane and her fellow teammates met with King Liones and young Elizabeth, whom she did not remember until 10 years later when Gowther revealed it.

10 years ago
The Seven Deadly Sins, including Diane, were summoned to a castle to meet the Great Holy Knight 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'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 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 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.

She 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 Cenette 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 Cenette 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. When Elizabeth apologizes to her for making them wait when she needed to heal but Diane said she shouldn't worry too much. When Meliodas was about to say where they should be going, a group of two apprentice Holy Knight who want to know where are they going and who are they because of Hawk mother and Diane being from the Giant Clan. Meliodas came out and told them that they are a traveling bar and that Diane and Elizabeth were they attractive waitress. The plan was working until Diane hugged Meliodas and call him captain because she was happy being called attractive.

When the apprentice Holy Knight was about to attack a Black Hound attack and killed them! Meliodas scared it away by using his power and they continued on they traveling. Meliodas told them that they are going to the Capital of the Dead to find King. When they got to a village next to the Capital of the Dead, they decided to find information to find King or how to get to the Capital. Meliodas picked Diane as one of the attractive waitress which made her happy and Ban was chosen to be the cook. Diane was standing outside all day to call people in but nobody came because the village was empty. The Sins realize that Ban left before starting business and decided to go out and find him. When they found Ban fighting someone, Meliodas stopped him and show who it is, both Meliodas and Diane recognize that person is King much to Ban shock. Diane went to him and told him that they been looking for him but King turned the other way and left. Diane and the others went back to the Boar Hat and were serving food to a local girl named Ellen and her brother.

They got information that King wanted to go to the Capital of the Dead and told them how do get there. When they left Diane was wondering why King left. When they got there the flowers around them started to move and made a wind which send them to the Capital of the Dead. Ban left the group to find something and they saw King following him. When they were trying to find them, a Holy Knight appeared to them and her named was Guila, she said that she killed herself to get here. Meliodas sense how dangerous she is and told Elizabeth and Hawk to leave. Guila launches an attack that sends the two Sins flying, but Meliodas manages to catch Diane before she fell on 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 using hand seal signs and made her move Sand Whirl to trap Guila in it but Guila easily frees herself with a blast from the tip of her rapier. She forces Diane back with another explosion but later comes back and tries to crush her but she dodges it with ease and explodes her again. But when all seems lost Ban came back and used his ability Snatch against Guila but she freed herself by using her power Explosion. The rest try to fight Guila together but she was too powerful and when Guila uses her explosion against Meliodas, Diane came in the right time and saved him much to her joy of how she saved him.

Diane was now blocking all of Guila attacks and now Diane is heavily wounded and couldn't move. But then King came in and told them that he is here to help them. Guila then sent a multiple of attacks towards them but King easily blocks them all with his spear. Guila then comments on his spear power and wanted to fight all the Sins but King said he wanted to fight one on one with her only and told the other to rest for now. After King defeated Guila, the rest of the Sins bodies were disappearing because the Capital of the Dead is rejecting them and are about to go back to the living world. When they got back they saw that Guila was there still in near death. Meliodas offers to do something to her before they leave. Later the Sins stopped to rest somewhere and Diane was feeling better now.

King was worried that Diane might still be injured from before and told her to rest but Ban told him that she might have faked it, so that Meliodas might pay attention to her much to King's dismay. Elizabeth comments at King of how strong he was which got King thinking and told the Sins that they could have beaten Guila with ease like him with their sacred treasures and asked them what happen to theirs. To King's shock he found out that the other Sins no longer has them, Diane lost hers somehow. King was now yelling at Meliodas and Ban for not having them but when he saw Diane doing a sad cute look he told her that she lost hers and it can't be helped.

Byzel Fight Festival arc
The next day, Diane is left behind 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 Byzel. When Elizabeth accepts the offer to join Diane the two then head into the forest to gather ingredients for dinner. 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. The latter wears the former's clothes and jewelry, in order for them to not be lost, and then, wanting to surprise Meliodas, enters the Byzel 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 Griamor. 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. Griamor, dismissing Veronica's worries about "Matrona" being Elizabeth, readies himself. As the battle begins, Diane immediately attacks Griamor, all of which are, negated by the Holy Knight's ability, "Wall". While Diane is being pushed outside the ring, Griamor states his intentions of humiliating Meliodas next. This enrages Diane, who proceeds to destroy Griamor's ability, and then defeats him, with a single punch. This greatly surprises both Veronica and Hauser, and causing Diane's hat to fall off.

As "Matrona" is declared the victor, and her facial appearance is now revealed to be identical to Diane's, 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 Meliodas, merrily expressing her elation at being held by him. She then asks Meliodas to grope her all over the body, as much 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 and King's 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 Hauser, Diane hurriedly hands Meliodas the shrunken Elizabeth and the princess' pendant, before leaving for the battle.

As the battle begins, Hauser 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, Hauser, 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, since she did not want her clothes to be torn. Finally able to unleash his powers, Hauser uses another technique, which causes Diane no damage again, leading to Hauser'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 Hauser from above. Hauser 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 Byzel. Ban and King also enter the ring, with Meliodas continuing that he will give the town a chance: he orders them all to leave Byzel, 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, Hauser 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 Hauser, as the earth collapses due to her increased weight.

After being dropped into the pit, Hawk's Mother appears before Hauser 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 Hauser if he is surprised of her true size, but Hauser told her he was not and was glad that she's okay. Diane then ask Hauser to take Marmas and the old man, and ran away which surprised Hauser, Diane then ask if Hauser will try to capture her, but Hauser told her that the Kingdom will be after them because of what happen to Byzel, but Hauser doesn't understand what to think of it. Diane later found her sacred treasure Gideon and headed 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 Gideon 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 Byzel, 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. Pelio 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's Mother 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 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 travelling towards Liones by foot along with Hawk's Mother, 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 Oslo to open his mouth wider.

Diane arrives at Hendrickson's magical research building, 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. Hauser 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, Hauser 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, Hauser and Guila steps in to protect Diane.

As Guila and Hauser 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 Hauser 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 Hauser 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 Hauser 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 and Elizabeth, but are teleported to a forest by 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 Griamor 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, 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 Kin'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.

Current 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 Six Stars of the Azure Sky: Death Pierce, Dogget, and Wayeo. Witnessing Dogget 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 Power 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, Hauser, and Griamor. 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.

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.

Abilities/Equipment
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.

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.

Abilities

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

Power Level

 * Magic: 900
 * Strength: 1870
 * Spirit: 480

Meliodas
Diane and Meliodas are both members of the Seven Deadly Sins. She is madly 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 and hits him for being close to other women. Her future dream is to become little and have children with Meliodas  She respects him a lot and calls him captain. However, her feeling of love toward Meliodas disappeared when she regain her love for King after regaining her memories, but still show respect and care for Meliodas.

Ban
Diane and Ban are both members of the Seven Deadly Sins. They are fairly friendly with each other, but as always, the only man Diane cares about is Meliodas.

King
Diane and King are both members of the Seven Deadly Sins. When they first met after ten years, she was happy to see him again and she might not realize that King is in love with her. When Diane was a child, she was extremely close to King, and told him to always love her. However, her memories were sadly erased, causing her to forget her time with King. However, after King saved her from Helbram, Diane soon regain her time with King and her love for Meliodas was replace with King. When King went missing, Diane grew upset and start shedding tears, as she wanted to tell him how she feels.

Gowther
Diane and Gowther are both members of the Seven Deadly Sins. They are fairly friendly with each other, but as always, the only man Diane cares about is Meliodas.

Merlin
Diane and Merlin are both members of the Seven Deadly Sins. Despite being female, Diane seem to like Merlin and has a good relationship toward her as she was displease when Merlin didn't rejoin the Deadly Sins. Diane hold Merlin very highly as she sees her as a genius due to creating her a pill that will shrunk her for seven hours.

Elizabeth Liones
At the beginning, Diane dislikes Elizabeth as she is jealous of her close relationship with Meliodas. She envies her small stature and her abilities to be able to take care of Meliodas when he is sick or injured. However, after seeing how courageous and brave Elizabeth was when she was willing to sacrifice 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 and even fought a Great Holy Knight just to get her back. Diane also support Elizabeth love for Meliodas after regaining her love for King.

Bartra Liones
None much is known about Diane and Bartra, but Bartra seem to trust Diane like any other Deadly Sins.

Hauser
Diane met Hasuer during Byzel Fighting Festival while disguise as Matrona and was shrunken during the time. Despite Hauser being the enemy, Diane shows no hesitance toward Hauser, possibly seeing him as a friend.

Dreyfus
Despite Dreyfus heavily injuring her and put her to near death, Diane still ask for Dreyfus help to rescue Elizabeth and doesn't seem to hold a grudge against him.

Guila
Diane and Guila were once enemies toward each other during the Capital of the Dead, however, when Diane was heavily injured by Dreyfus and was being framed by Helbram. Guila quickly join Diane side and Diane doesn't seem to hold a grudge against her from her past action, even accepting her help to protect herself and rescue Elizabeth.

Baste Dungeon Arc

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

Capital of the Dead Arc

 * Meliodas, Diane & Ban vs. Guila: Indecisive

Byzel Fight Festival arc

 * Griamor vs. Matrona (Diane): Win
 * Matrona (Diane) vs. Hauser: Win
 * Meliodaz vs. Matrona (Diane): Draw, interrupted
 * Diane vs. Helbram: Win

Kingdom Infiltration arc

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

Trivia

 * Diane is a very common given name, and the Roman name of the Ancient Greek deity, Artemis.
 * She relishes whole roasted pigs.
 * 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.
 * 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.

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Diane