Momoko, whose husband passed away three years ago, has been single-handedly raising her son Kazuya. However, his grades in school have not improved, and the stress of education has caused her sexual frustration to grow. She cannot resist the vibrator she confiscated from her son's friend Shunsuke and masturbates. Shunsuke happens to see her doing so. Momoko's sexual desires run wild, and instead of scolding him, she grabs his fully erect penis and begins to stroke it greedily.