One day, while her husband was away, Yuka, the stepmother, and her stepson Yūsuke had a physical relationship. Yuka was tormented by guilt and a sense of transgression, and tried to end the fruitless relationship, but Yūsuke enjoyed the status quo. Yūsuke's youthful libido knew no bounds, and it became increasingly uncontrollable, eventually leading him to seek Yuka's body as soon as his father left...