Sensou no Akuma

Yoru is the War Devil and a member of the Four Horsemen, who now occupies Asa Mitaka. Before inhabiting Asa's body, her appearance was that of a bird, largely resembling a potoo.

Yoru is first seen on top of a traffic light a few seconds prior to Asa Mitaka's death by the Class President's Justice Devil Form. She resurrects Asa in exchange for inhabiting her body, leaving half her brain intact to keep her alive.

War Devil calls themselves "Yoru" so that it's easier for Asa Mitaka to call her. It is also revealed that there is a condition in which Yoru (War Devil) cannot take over Asa Mitaka's body when she is stricken with fear.