Sung Woo, the successful animal communicator, especially has a lot of female clients. He doesn't stop any women who try to hit on him, but he actually has a girlfriend. Joo Mi is a devoted girlfriend who works as a vet and lives with him.
Leo is Sung Woo's business partner and the genius monkey, and he has been going out with Joo Mi's companion dog, Juliet, for a long time as well. Their peaceful days last until the 2,000th-day anniversary when Sung Woo's reckless behavior ruins everything. Leo and Juliet happen to be at the verge of a breakup because of their owners, and the two start trying to bring them back together.