Eunju is a timid, slightly gloomy twenty-year-old with a secret she can never tell anyone. Whenever she holds hands with a man, her body reacts far more intensely than it should. Her quiet life takes a sharp turn when her sunbae Hyeyeong, a self-proclaimed expert in “adult matters,” discovers Eunju’s secret. From that moment on, Hyeyoung decides to take Eunju under her wing, and the two embark into a wild world neither of them came prepared for.