Asa Mitaka is a 17 year old high schooler that is 5'6 in height. Yoru resurrected and inhabits Asa's body, turning her into the War Fiend, but left half of Asa's brain intact, keeping Asa alive. Only one of them has control of the body at a time and they can hear the other person's thoughts during this, which is irritating for both parties. Yoru tries to blend into human society but is very unfamiliar with it, and needs to be taught. They aren't fond of eachother, but they tolerate eachother.