Satoru lost his mother when he was young and now lives with his father and his new wife: Kyoko. One day, Satoru witnessed his father and Kyoko having sex, and from that day on, he started having trouble sleeping (and having trouble getting erections). Kyoko finds out and tries to teach him sex education… However, wanting to help, she goes too far. Nagae will actually go there. And Machimura Kyoko is so sexy, what a performance.