Yuko, the mother of Yamato's childhood friend, held a special place in his heart. She was his first love, and the reason he kept visiting the Shiraki household wasn't just to see her—it was because he'd noticed subtle changes in her behavior, and it worried him. One day, Yamato accidentally witnessed Yuko masturbating. Shocked by the scene, he felt an overwhelming desire to comfort her. But he knew she would never allow a relationship with her son's friend. So he made a decision: he would secretly record the act and use it as blackmail.