Airi enjoys her married life, having been in a close relationship with her husband since school days, and also maintains a good friendship with her best friend Mika and her husband. Her husband joins their monthly dinner gatherings and treats everyone kindly. The couple's rule is to keep no secrets from each other. However, Airi has betrayed both her husband and her best friend, secretly building a relationship with Mika's husband, Junichi. When her husband leaves for work, Junichi visits her home, and Airi transforms into a completely different person, exposing her slutty, submissive side. Though she swears each time that it will be the last, her heart is drawn to Junichi, and she continues their illicit affairs.