Tsuki no Umareru Yoru

When Akitsu Makoto was a child, he tripped and fell at a shrine and was comforted by a strange being he belives was the god of that shrine. Years later when visiting a festival with his cousin Shou, he sees the god in the crowd and chases him to a shrine to thank him. The god, who is actually a kitsune spirit, tells him that because humans are destroying the environment and the shrines, and no longer believe in him he has lost his power. Jump forward to high school, and Makoto and Sho have inherited abilities as the decendants of the Akitsu clan to communicate and fight with demons and ayakashi.

(Source: M-U)