Polyphonica

In the continent of Polyphonica, Spirits materialized in the world, surviving on the music that is played by humans, and lives together with them. While the spirits don't appear often, some spirits has enough power to materialize in human or animal forms and live together with humans. Dantists, who play special music called “Commandia,” are widely respected in this world. They also usually are in contract with powerful spirits. The new Dantist, Pholon Tatara, makes a contract with, Coathicarte Apa Lagranges and works with her.

Synopsis from Anime News Network