Today's Cerberus Vol. 2 (manga)

Thus far, Chiaki has been settling in to his new life with his new, semi-canine companion(s), but happiness still seems a hair out of reach. Of course, it doesn't help that his partially soulless nature has left him a target for monsters. And speaking of monsters, it seems one of Chiaki's classmates has a companion of his own, only this one is of the feline variety. You know what they say about cats and dogs...