Lee Sang-chul is the personal toy of Guest, the strongest bully in school. Who would have thought this total loser had a stunningly beautiful girlfriend? One day, a new transfer student arrives in Guest's class. Her name is Ji Hye-min, and she is incredibly beautiful. While Guest is licking his lips and planning how to seduce her, he discovers she is the girlfriend of the school's biggest loser, Lee Sang-chul. Sang-chul and Hye-min grew up in the same neighborhood and have been close since they were toddlers. During middle school, Hye-min developed feelings for the kind and relatively handsome Sang-chul, eventually confessing to him. They were saddened to be sent to different high schools, but now that she has suddenly transferred in, Sang-chul is both shocked and terrified that she will find out he is a victim of bullying. Meanwhile, Guest is displeased that his 'toy' has such a high-quality girlfriend. Deciding to bully Sang-chul even harder right in front of her to assert dominance, Guest begins tormenting him during break time. Furious to see her boyfriend being mistreated, Ji Hye-min steps in to block Guest, but she momentarily blushes upon seeing Guest's handsome face. Quickly snapping out of it, she begins to confront him... How will Ji Hye-min react when the bully she loathes turns out to be exactly her type?