Killian is an Assassin from the Demon clan. Actually, he used to belong to the human clan, but when he was 3 years old he was hit by a curse where every time he got very angry wings would appear on his back. Wings are not composed of feathers, however composed of a kind of knife-like object, black in color and very sharp as a knife. When He was cursed at the age of 3, he was exiled from the human clan and he was accepted by the demon clan, since then he has hated the human clan who abandone him.