Asa Mitaka is a shy, introverted girl who's very awkward, doesn't like to talk much. She always feels nervous and awkward around people because she got bullied before. Yoru took over Asa's body and occupies half of her brain. Yoru is a war devil, one of the four horsemen of apocalypse that is manipulative, seductive, violent, strong, immature, calm and smart. She would always give advice to Asa and tell her what to do. They also argue a lot and Asa can't reveal Yoru.