Prior to Catastrophe, Asuramaru was a vampire known as Asura Tepes and is from the same family as Third Progenitor Krul Tepes. He gets convinced by the First Progenitor to travel with him to the island that will become Japan and become a demon as he must "go for their future". His disappearance with the First Progenitor prompts Krul's search for him. Many years after his rebirth as a demon, Asuramaru is sealed within a katana by humans and chained in place by a curse where he becomes Mahiru Hīragi's weapon. After Mahiru's death, he becomes recognized as part of the Black Demon Series.