Series by 渡辺ペコ

Ichiko and Otoya are a friendly couple in their thirties after seven years of marriage. They have no children and are no longer physically intimate. To keep their marriage going, they choose a rule that permits outside romance. Otoya becomes absorbed in his approved relationship with Mitsuki. Watching him changes Ichiko's own feelings about desire, jealousy, and married life.

Atsuko and Kouhei have known each other for nine years. They have lived together for five of those years. Near age 30, they remain close but hesitate over marriage and children. Their relationship begins to shake when Kouhei learns he is going to become a father. The early material follows two adults forced to reconsider a life that seemed stable.