The Purpose of An X-Rated Encounter(19금 만남의 목적)

Min-joong and Ga-hee are a campus couple and friends with Geun-tae. Geun-tae has a crush on Ga-hee and asks her out to dinner to tell her how he feels about her. Ga-hee knows how he feels but she tells him she is in love with Min-joong and doesn't acknowledge his feelings for her. Geun-tae isn't happy with how Min-joong treats Ga-hee and feels bad for her. So Geun-tae comes up with a plan to break them apart by introducing a girl named Eun-bit to them...