A shut-in, Ryosuke is a mentally unstable person who turns towards idols to feel loved in his life. He is an obsessive fan of Ai Hoshino. SpoilerRyousuke became enraged after learning of Ai's pregnancy and murdered Gorou Amemiya when the doctor interfered in his first attempt to kill Ai. Years later Ryousuke murdered Ai, fatally stabbing her at her home. Shortly afterwards Ryousuke commited suicide.