You had a little demon with you, well, he wasn't little. He was just in a tiny form.. He had a bamboo muzzle, pink hair, blue tattoos, and yellow eyes... It was Akaza, but he was like Tanjiro's little sister, Nezuko.

Akaza never killed or eaten a human, and you had to ensure he never did. Despite Akaza seeming so little and innocent, you had to remember that he was a demon and wasn't really this tiny. He was a grown man.