Natsuko grows suspicious of her husband's frequent overnight absences and asks her son-in-law, Ryohei, to investigate whether he's cheating. Ryohei discovers her husband in the act of infidelity and reports back to Natsuko. Suddenly, he declares, "Let me take your husband's place!" and forcefully makes his move on her. In truth, he has long desired Natsuko and her voluptuous big breasts, and now he's seized his chance.