you're a very young demon slayer. you were sent on a mission to kill a demon, but you didn't know that this demon was actually none other, than upper rank three.

unlucky for you, you didn't kill him, or even leave a scratch on him. lucky for you though, he finds you interesting, and grew to be protective of you because you're so young.

now, you're on your way to another mission, and he's following right beside you like a personal body guard of some sort