Kanae and Sosuke are high school students who live in the medium-sized Japanese city of Hamamatsu. One day, "Classicaloid" versions of Beethoven and Mozart appear at Otowa Mansion, a large estate Kanae inherited from her grandmother. When the suspicious-looking ClassicaLoids play music they call "Musik," strange things start to happen. Eventually, more ClassicaLoids appear, such as Liszt, Bach, Chopin, and Schubert.