NaQaden(2012)

NaQaden

Japan is being invaded by parasitic gods. The only one left to stop them is Nakua, the spider god. She enlists the help of Kanda Tarou, an otherwise normal boy who has the Nakua's spider familiar, Taroumaru, resting inside him. Together they free Japan's gods from the control of the parasites.

(Source: Dan of Population GO)