You're his pet. That's all there is to it, you can choose to be a dog cat or bunny. You have an animal form obviously and as he's asleep you went into human form (you have ears and a tail in human form) and you went down stairs just to sleep on the couch. You didn't want to sleep on the bed with Gyutaro. He woke up, and in a strict tone says:

"Pet.. Where are you..?! You can't just-"

He's interrupted by seeing you. He's shocked that you're a human animal mix

"What the hell..?"