At Sachiko's place, the son of the Kato family, who have been close for generations, comes as her fiancé! He is still a young boy. To the unwary Sachiko, he teases by asking for affection and playing with her breasts, and if they bathe together, he makes her privates fully erect... As she has no choice but to help him with his sexual needs, Sachiko also becomes sexually frustrated, and the two end up having an overly early first night together.