“It’s so hard that I don’t think it’ll be easy, but I’ll try to loosen it up as much as I can.”

Arin, a competitive swimming student, has a routine she follows at the end of every day:
a secret moment of self-pleasure to improve her “quality of vaginal life.”

One day, as usual, she is about to masturbate while watching an adult video when Shin Juwon—her older brother’s friend and the perfect embodiment of her ideal type—asks her to help him practice massage techniques for a certification exam.

But for some reason, the hands that had been massaging her body begin to stray toward increasingly intimate places…