Mari lives with her husband and son. The son enjoys spying on his parents' nighttime activities and then masturbating. One day, Mari goes to call her son to his room. When she opens the door, she finds him masturbating. 'Being seen by my parents is the worst,' the son pouts. 'Masturbation isn't something to be ashamed of,' Mari tries to convince him. However, the son demands that she watch him masturbate. From that day on, Mari can't stop her relationship with her son. She becomes engulfed in the forbidden pleasure with her son...
