"What goes around, comes around." (My Demon Slayer AU)

Tanjiro is well on his way to become a successful demon slayer. But, along the way, he meets a few people that may change his life forever. And they aren't particularly normal, far from it, actually. They seem benevolent, and seem to want to help him on his journey. But, he soon realizes the past of these individuals is covered by a fog of mystery. And he isn't sure if he wants to find out what's behind that mist.
(This also includes some characters from the DSMP)