A young married woman, "Minase Miya", who is a swimming instructor teaching children how to swim at a fitness club in Tokyo, appears in this adult video. Miya-sensei is very popular with students and parents alike for her gentle, motherly smile. But in reality, she is a lewd married woman who is not satisfied with sex with her husband and indulges in masturbation every day. During her first affair in her life, she climaxes from the pleasure of a stranger's cock, something she has never experienced before.