He is the pilot of a robot squad designed to fight monsters called Arch Dissolvers, weapons created by an unknown force. He is also the fiance of fellow pilot, Hikari, having sex with her twice, once in the bath, and one on the bed. During one of the battles with an Arch Dissolverm Hikari, Ru, and Kyosuke are hit with a psychological attack. Kyosuke meets an evil version of himself, who appears in Hikari and Ru's dreams, raping them in their mind.
Hikari was injured in the attack, much to Kyosuke's worry. Due to the attack, Ru begs Kyosuke for sex due to past trauma. Though he loves Hikari, he knew the importance of what was going on and he obliges, taking Ru's virginity as a result. Kyosuke enjoys himself and agrees to do it again with Ru.
During the final battle with the Arch Dissolver, which was reaching critical mass, they destroy the monster's core but it regenerates but spares them, with higher ups believing it to be a diversionary tactic. Kyosuke goes to Hikari, telling her the doctor gave them both permission for sex. However the the psychological attack takes it toll on Hikari, who begs Kysoke to stop.