Eun-joo, a gloomy and timid 20-year-old woman, has a secret she can’t tell anyone… Whenever she holds hands with a man, a flood breaks loose down below. When Hye-young—an upperclassman at the same school, and also known as a “chairwoman”—discovers Eun-joo’s secret, Eun-joo’s life suddenly turns mischievous, bold, and overflowing with risqué energy…