Mori no Kuma-san, Touminchuu.

Nowa the bear lives in the forest and adopts a puppy named Airi. Before going into hibernation, Now was worried that Airi wouldn't wean. A few months after starting his hibernation, Nowa wakes up with a pleasant sensation from Airi, now an adult dog, licking his nipple saying, "I've been waiting for a long time." (Source: MAL News)