What would you do if the dog you picked up transforms into a human that wants to do "stuff" with you?

Ma Sung Jun does part-time job at animal adoption cafe. One day, after finishing his shift and going home, he finds a lost dog of mysterious species. In usual cases, he likes cats more than dogs, but for some reason he takes the dog home. He calls the dog Tani and leaves his home to get things he needs to take care of Tani. When he comes home he finds Tani is no longer a dog?