Stepmother Yuu repeatedly engages in lewd sex with her husband even while her stepson is home during the day. Her actions intensely stimulate Anhiko, a college prep student, quickly arousing him. As this continues, Anhiko begins to see Yuu as a woman. Sensing this, Yuu increasingly turns her attention toward her stepson, and eventually the two become involved. From then on, the son seeks his mother's body even while his father is present in the house, beginning days of unrestrained passion from morning until late at night. A heated relationship unfolds, entwined with adultery and family conflict.