Living together in married life, Mizuki moves into her husband's family home, beginning a new life in the countryside. However, her husband has a younger brother who gradually starts showing lewd interest in Mizuki, with his actions escalating further over time. When Mizuki discusses this with her husband, she learns he is troubled by his brother's behavior—and ultimately decides to personally open Mizuki's body and teach his brother how to enjoy her pleasures. As a result, the younger brother begins seeking pleasure from Mizuki's body, and upon witnessing the scene, the husband himself starts turning his attention toward Mizuki's body as well.