Yoru, also known as the War Devil or War Fiend, has a bird-like body reminiscent of a dark owl or potoo. When possessing Asa Mitaka's body, she has three scars on her face and her eyes have multiple rings. Yoru is confident, prideful, and views humans as tools and beneath her. She is cunning and intelligent, able to blend in and manipulate others to achieve her goals. Her driving force is to defeat her rival, Chainsaw Man, but she also shows a level of respect for him.