Inukami!

Inukami: a sacred being with a dog-like appearance that forges a contract with a powerful human tamer to help them eliminate evil monsters and demons.
Though Kawahira Keita is the descendent of a long line of Inukami-tamers, he seems to lack the necessary ability and has been forsaken by his family. One day, he meets a cute Inukami named Yoko, who, at first glance, looks graceful, obedient, and beautiful...but upon forging a contract with her, Keita discovers that Yoko is a wild and mischievous Inukami that no one has ever been able to control.
(Source: Seven Seas)