Polyphonica is a place in which humans and spirits coexist; spirits gain their energy from the music of humans known as Dantists. The spirit Corticarte and her Dantist Phoron, along with their friends in the Tsuge Divine Song Players' Dispatch Office, take on cases to help the population deal with problems requiring their unique skills. As they go about their day-to-day work, they learn more about the nature of the cooperation between humans and spirits, as well as their relationship with each other.