Yukina Momose is a newly appointed Japanese language teacher at a school, proud of her fair skin and toned, shapely big ass. Recently, she's been in high spirits after her homeroom class won first place at the school sports festival. Three years after marrying her husband, she appears to be living a smooth and happy married life. However, before marriage, she was trained by a former boyfriend who instilled in her deeply deviant sexual desires. As a result, she's become addicted to having sex outdoors. On her days off, she willingly offers herself as a sex slave, eagerly sucking strange men's cocks in public. The more extreme the masochistic acts become, the greater her pleasure grows—yet she's terrified by the person she's becoming.