The day Lee Joon joins Minsong University to reunite with Kim Margo, his high school crush, he is attacked by his new neighbor Lee Duna, a gorgeous former idol. Violent and impulsive, Duna turns Joon's world upside down. Later, to Joon's confusion, Margo seems incapable of making time to meet with him. To add to his dismay, Joon meets fellow student Choi Ira at a party. She becomes enamored with him after the pair partake in a risqué game. As Joon progressively discovers the truth about Duna's troubled past and Margo's harsh family conditions, he tries to sort out his tangled feelings.