At a hotel for their anniversary, Ichiko makes an advance on her husband. She is shocked when Otoya rejects her because of his mistress, Mitsuki.

Ichiko finally opens up to Otoya about her painful past when they visit her mother; Mitsuki warns him that they need to be more secretive with their dates; Ichiko visits a secret brothel for women and finds herself charmed by the young Rei.

Ichiko's intimate session with Rei is unfortunately cut short when she rushes home to nurse an injured Otoya. However, her guilt nags at her as she cannot stop herself from thinking about Rei.

Ichiko and Otoya enjoy a happy, sexless marriage, content with Otoya's affair with Mitsuki. When Otoya rejects Ichiko on their anniversary, she considers her friend's advice to find her own boyfriend.

Ichiko and Otoya decide to rekindle their sex life, but their excitement quickly turns into frustration. Otoya is haunted by Mitsuki's curse-like words of goodbye and Ichiko cannot stop comparing him to Rei.

Ichiko and Otoya have been married for seven years, but unbeknownst to those around them, they are in a sexless marriage, have no children and share a secret: every month, Otoya spends the night with his `lover.'