The blue demons are giant, bird-like creatures with muscular physiques. Their arms resemble wings and they have coxcomb-like features on their heads.
The blue demons are first seen when one comes flying by Diane, frightening her as it roams around villages, distributing posters for the fight festival. Once they're done, they return to two of the Commandments, but are one member short.. That demon preyed on Sol and Della, but then got crushed by Matrona.
A pair of Blue Demons are part of the Fight Festival being the opponents of Ban and Meliodas. The demons attack them quickly, but the Sins limits to fool around among themselves without paying attention to them, ending up killing them in the process without realizing it.
The last Blue Demon is killed by Silver.
Various Blue Demons are part of the Demon Clan army that is faced by the Holy Knights during the Holy War. They release their attacks against the knights. One of them is seen being killed by Deldry. The rest are eliminated by Diane's Queen Embrace and the Four Archangels's Omega Ark.
Various Blue Demon attacks Guila during the second wave of the demon army, but are eliminated by Elaine. Various others are killed by Matrona's Daichi no Kiba. An Blue Demon tries along with several other demons to devour Elaine when she falls, but all are killed by Ban.
Abilities and PowersEdit
They have the standard demonic power of darkness, being able to use it to form wings to fly. According to Meliodas, they are known for their speed.
Blue demons also have the ability to fire explosive balls from their mouths.