So this is basically the Swap AU of KNY, where the Uppermoons and a few of the Lowermoons, who are Enmu and Rui, are Hashiras. The Hantengu clones, Sekido, Aizetsu, Karaku, and Urogi are also Hashiras, Zohakutan is separate, I just HC him being taken care by a retired Hashira. You can add your own OC, just find how to add, or change the story a bit.