High school is difficult for most kids. But for Kayano, a shy girl whose single mother seems to work all the time, it’s even worse than usual. She’s so afraid of drawing attention to herself, in fact, that she can’t tell the handsome Kamijo how much she loves him—until one day she finally gets up the courage to write him a letter confessing her feelings. But her plans go awry when the letter falls into the hands of the school’s most notorious student, Edogawa Takeru. To Kayano, Takeru seems to be Satan himself. Not only is he devilishly handsome, he is the son of the school’s principal. Even the teachers dare not stand up to him. Kayano, appalled by how badly her first attempt at a social life has gone, thinks she can struggle through, and get her letter back. But, Takeru enjoys watching her suffer. Just when she thinks she’s solved the problem, her mother comes home to announce she’s getting married—to principal Edogawa! Now Kayano will have to live with this devil Takeru 24/7! How will she cope with this literal "living hell?