From Renta!:

Volume 1:
Katsuyuki returns to the town he lived in as a child after being away for ten years, but he's faced with nothing but trouble. In order to try warding off evil spirits, he goes to a shrine to pray. There, he meets an oddly-dressed child with furry ears and a tail, who only Katsuyuki can see. The child follows him home, asking to "feed," and proceeds to kiss Katsuyuki and swallow his spit... "What the? Did he just get taller...? And now he wants to mate with me...!?" The threads of fate interweave in this mysterious anthropomorphic fantasy!

Volume 2:
Akinori's a rookie high school teacher. On his way home one rainy night, he finds an injured puppy and takes him home. However, he awakes in the morning to find a human child with dog ears and a tail!