Asa Mitaka is the main protagonist of the Academy Saga. She is a high school student who became the host of the War Devil, Yoru, making her the inhabitance of the War Fiend, though she still retains her human personality when Yoru allows her control, making her a rare case of a living Fiend host. She attends Fourth East High School with Denji, with whom she briefly attempted to start a relationship with, ending in disaster, though she develops a crush on his alter-ego, Chainsaw Man instead.