窮鼠はチーズの夢を見る

Due to his indecise nature, Kyoichi, an advertising company employee, repeatedly cheats on his wife. One day, he meets Wataru, an old classmate from university. Wataru reveals that Kyoichi's wife hired him to investigate whether Kyoichi is having an affair. Wataru, who has liked Kyoichi for the past 7 years, takes advantage of the situation and blackmails the salaryman: if he accepts to have a sexual relationship with him, he won't tell his wife about his infidelity.