Nanami lives with her mother and leads a marital life at her parents' home. Recently, she has been having many days of missed connections with her husband, who is often too busy with work to attend to the family. One day, her sister Keiko returns home with her husband, Toru. After dinner, accidentally left alone with Toru, Nanami ends up venting her complaints about her own husband, unaware that Toru is also struggling with a cold relationship. Sharing their common troubles brings them closer, and the two, caught in a forbidden relationship, are unable to resist their desires and gradually fall into a double affair.
