One day, Daisuke spots his friend's mother, Waka, getting intimate with an unfamiliar man and immediately realizes the man must be her lover. Instead of leaving, he follows them and peers through the window of Waka's room, witnessing the two engage in lewd acts. In that moment, Daisuke secretly records the scene on his mobile phone. Later, he visits Waka's home as if nothing happened and blackmails her by showing the incriminating photos. Powerless and exposed, Waka is forced to submit to Daisuke's demands.