Fumiko has had a relationship with her only son, Katsu. In order to keep it a secret from her husband, she has been having sex with him very carefully, but as an adolescent, Katsu becomes obsessed with the pleasure of sex and becomes bolder. Fumiko is worried that her husband may find out at any moment. However, as he continues to hold her in his arms, he is no longer able to control his sexual desire. Today, the moment her husband leaves the house, the two share a passionate kiss...