Goshujinsama to Kedama

Chigusa is a businessman who lives alone. One day he picks up a dirty hairball-like animal, thinking it's a cat. He washes and feeds it and puts it to bed, but the next morning... in the room there's an adolescent with cat ears and a tail, which Chigusa has never seen before. He calls Chigusa "Master" and wants to serve him hard, so Chigusa names him "Kedama" (hairball) and they start living together, but...

(Source: Gentosha Comics, translated)