Aoi Okana is 40 years old. She has maintained her perfect H-cup figure and slim waist, which is hard to believe for a housewife. She has been married for 16 years and is the mother of one child. As she gets older, her adult charms grow stronger, but her husband, who is a worrier, restricts Aoi, who wants to work outside, and locks her in a cage at home. However, her husband comes home late, so their nighttime activities decrease year by year... Aoi is a laid-back person who has never asserted herself, but the stress she has been holding for many years finally explodes. "We had our first fight as a couple." Her sexual desire, which can no longer be controlled by masturbation, gives rise to the desire to cheat, and in her 40s, she opens the door to infidelity for the first time in her life.