Mamoru lives with his brother and his wife Miki. One day, while he is resting with a cold, Miki comes to look after him and he can't help but fantasize about their bodies touching. However, one day he witnesses an affair between his tutor and Miki, which shocks Mamoru and arouses his desire. He blackmails Miki by hinting at a forbidden affair, sneaks into the couple's bedroom while her husband is asleep, and approaches her...