"It looks pretty firm and won't be easy, but I'll loosen it up as much as I can." Arin, a sports scholarship student specializing in swimming, has a nightly routine to wrap up her day: a secret self-care session to improve her quality of life. On a night like any other, just as she was about to indulge while watching adult videos, Shin Joo-won—her older brother's friend and the man of her absolute ideal type—asked her for a favor: to practice massage techniques for his upcoming license exam. However, for some reason, the hands touching her body keep wandering toward more intimate places...