Yoon Ji-Hoon, a college freshman, falls in love with his beautiful classmate Han Ah-Reum. In a wave of confusion, he assumed that Ah-Reum was waiting for his confession, only to get rejected. In desperation, he unconsciously summons the demon of desire, Mephi. Ji-Hoon signs a contract stating Mephi shall help him in the next 6 months to make Ah-Reum fall in love. If she still doesnt give in, Mephi will be forced to take Ji-Hoon soul in exchange.