While heading to her first day of high school, Eri Kumagai is drawn in by a girl"s melodic voice. The song is beautiful until the singer steps on a cat"s tail, abruptly ending the moment. Eri pushes the memory away until that same girl rushes into her classroom late, cat in hand, and declares that the name on the attendance sheet—Chiharu Yuzuka—is a false one; her real name is Haru Chitose.
Eri, disinclined to accept the eccentric newcomer, finds herself unable to avoid her because they share a dormitory room. Haru brings one headache after another, yet when she snoops through Eri"s laptop and discovers that the girl is an online composer, Eri is furious. Enamored by Eri"s music, Haru desperately wants to sing with her, but Eri is adamant. Will the two eventually find common ground?