Pretty Young Sister 2.

Dong-hoon and Min-soo, who are college friends, are best friends with their boyish female friend Ji-hyeon from the same department. Min-soo secretly likes this kind of Ji-hyeon. One day, Ji-hyeon, Min-soo and Dong-hoon drink casually, and Ji-hyeon makes a mistake. Ji-hyeon, who drank a lot the day before, seems to have slept with someone, but she can't remember whether it was Dong-hoon or Min-soo. But Ji-hyeon is more confused by the behavior of two men who are so indifferent... Was it Min-soo who spent the night with Jihyeon? Was it Dong-hoon? The sweet, gruesome love story that falls into an unknown mystery is just beginning.