Toshio lives with his son and daughter-in-law, but he has one secret struggle: he feels a hidden excitement whenever he overhears the couple's intimate moments. Ashamed and guilty for having such desires, he still can't suppress his arousal. One day, when his daughter-in-law, Tsubasa, unknowingly comes close to him, he feels an uncontrollable urge, pins her down, and takes her. Overwhelmed by the intense, ravenous passion that her husband never showed, Tsubasa gives in to the throbbing pleasure. Awakening to this new ecstasy, Toshio continues to claim her again and again, until she gradually accepts their forbidden relationship. Their illicit bond grows deeper each time.