A housewife named Miho, who had given up on making babies with her husband due to his poor health, one day discovers a brothel flyer in her husband's suit pocket and learns he has registered on a dating app. Though shocked, Miho still loves her husband and hesitates to cheat. However, after finding anal-only porn in his room, she begins to think that engaging in anal sex might not technically count as infidelity. As an act of defiance toward her husband, Miho starts enjoying anal sex with a man she meets.