Hiroshi misses the last train and ends up staying at his friend Yutaka's house. When Hiroshi wakes up in the bathroom, he sees Yutaka and his beautiful fifty-year-old mother engaging in forbidden acts of devouring each other's genitals. Incest between a friend and her mother. Hiroshi, who feels abnormal excitement, visits his fifty mother when Yutaka is away. The fifty-year-old mother, who has a strong libido contrary to her beautiful and neat appearance, has not only her son but also her friend Hiroshi's meat stick in her mouth and has been crazy with pleasure.