In this story instead of Tanjiro being the older brother he is the younger brother (He's also the one to get turned into a demon by Muzan) Nezuko is basically the older sister in this Story.Basically the Hashira are different Shinobu,Giyu,Sanemi, Muichiro,Mitsuri,Obanai and Gynoemi and Yoriichi are all demons while Gyokko,Nakime,Daki,Gyutaro Kokushibo,Douma,Akaza, Hantegue, Kaigaku, are the Hashira's. And the Lowermoon Enmu (Lower moon 1) Rokuro (Lowermoon 2) Mukago (Lower moon 4) Rui (Lowermoon 5) Kamanue (Lowermoon 6) Kyogai (New Lowermoon 6) Are all Demon Slayers