Tsubaki was living alone while her husband was away on a business trip. Then her newly married daughter and son-in-law came to live with her out of concern. Although Tsubaki's loneliness had eased considerably, she couldn't help but feel a physical throbbing... One night, she accidentally witnessed her son-in-law Yasuo masturbating. Her massive penis left her speechless and unable to control her reason, and she tried to seduce him in every way possible. Unable to resist his mother-in-law's provocative eroticism, Yasuo became more and more addicted to her...