Mahiru Yanase's twin sister, Mayo, has it all—she's cute, sweet, and popular. Mahiru, on the other hand...has always been the other Yanase. All her life, Mahiru's reminded herself that every time something good happens to her, something bad comes along to balance it out. She never gets her hopes up...but no sooner does she arrive for her first day of high school than Aoi Satomi, her handsome, mysterious classmate, takes an interest in her—and by the end of the day, he's already asked her out! If things don't balance out for Mahiru soon, the world's going to come to an end!