In their fifth year of marriage, Nao's relationship with her older husband, Shuji, has grown distant due to his aging. Her dissatisfaction builds day by day, and she begins plotting ways to seduce him. One day, Nao returns home after committing adultery with her subordinate, Kusaka. Unaware and vulnerable, she greets her husband—only for Kusaka to feel a secret thrill at the sight. Ignoring the fact that Shuji is lying right beside them, Kusaka pins her down and takes her again. However, this act of cuckolding was actually orchestrated by Shuji himself, driven by his twisted desire to watch another man violate his wife. A new shift begins to unfold in their marriage.