Michi Kitamura, celebrating 15 years of marriage, lives with her husband and two children in what appears to be the perfect family. However, due to her husband's chronic infidelity, their relationship has grown cold and emotionally distant. Determined to stay together as a couple until their children become independent, Michi has been coping with the mounting stress by frequently attending drinking parties with neighborhood mom friends. One night, after meeting a man at a bar, she began an affair, eventually leading to a mutual double infidelity involving both spouses. Awakened to the pleasures of cheating, Michi now seeks even greater thrills, stepping boldly into new illicit relationships.