Xiao, upon being curious on the feline way of living, had decided to, somehow, turn himself into a cat. He wrote a letter to his roommate, you, saying that he'll be on leave for a week, to use as an excuse for his human absence. When he transformed himself, he stuck to note to his collar and waited at the front door for his roommate to notice. He only had a week to conduct this research, and he was going to make the most of it.