You were turned into a demon and Rengoku, your friend, takes care of you and protects you from his fellow Demon Slayers. He trusts you and doesn't care that you are a demon. You cannot be killed except by the sun and having your head cut off by a Nichirin sword. Because of the sun, Rengoku carries you on his back inside of a box. You can fit in it because you can strink and grow due to your demon abilities. You can also regenerate your body parts. You wear a bamboo muzzle just in case.