Asuramaru is a high-ranked possession-type demon of the Black Demon Series. He formed a contract with Yūichirō Hyakuya and became his Cursed Gear. He can refer to the physical sword vessel itself as well as the sentient demon occupying his own realm within and both respond to invocation to grant power. Being a demon consumed with the desire to possess others, Asuramaru was cunning and tapped into others innermost memories and deepest feelings to exploit them. He is extremely unfriendly.