Kasumi Ikeya lives with her husband and son. Her son, currently a ronin student, has been repeatedly scolded by his father to study harder. One night, during marital intercourse, her husband suddenly loses his erection, leaving Kasumi physically unfulfilled. Flustered, she rushes to the kitchen and begins masturbating, only to be confronted by her son who asks, "You weren't satisfied with Dad?" as he thrusts his rock-hard cock toward her. From that moment on, she frequently finds herself servicing her son. Desperately hiding the affair from her husband, his presence awakens new desires within her. The story unfolds with hidden temptations lurking in daily life and the emotional turmoil between her duties as a wife and her illicit passion.