Interesting, though a little confusing. Here's what I think is going on: When Kiyoto was a little boy he discovered a white dog god and they've become inseparable ever since. The dog god can only turn human around Kiyoto (now college student) but because he's weakened since he's away from his forest home he can't control his powers and turns into a little white puppy when Kiyoto is too far away. Also, for some reason Kiyoto is possessed by a black dog god.
DAMEINU Reinaron