"Machi" and "Ken" are lovers. Machi, who is aggressive and has a tendency to be forward, and Ken, who is submissive (M), have an S&M relationship. Hiroshi, the father who knows nothing about this, becomes curious about the noises coming from their room one day and ends up peeking inside. What he sees is his son being anally penetrated by his girlfriend! Ever since then, Hiroshi can't stop thinking about Machi. Machi, sensing this, seduces and toys with her boyfriend's father, making him addicted to forbidden pleasures in the room without her boyfriend...!
