The blunt and inflexible college student Kwon Jeong-ha absolutely despises Gwak Hyun-woo, his handsome and popular classmate who toyed with and then dumped the senior Jeong-ha had secretly been in love with. The two are like cats and dogs — growling whenever they meet. But one day, because of a strange necklace Jeong-ha picks up, their relationship is completely turned upside down. “It’ll probably sound crazy, but… I’m a demon.” Hyun-woo, who claims to be a demon, tells Jeong-ha that all the magical power he had stored inside the necklace has been absorbed by Jeong-ha — and that unless he gets it back, Jeong-ha will die. The only way to return the magic… is through physical contact! And so, Jeong-ha ends up living together with the demon.