This is an au, all roles in demo slayer are swapped.nezuko being human as she is now find a way to cure her demon older brother tanjiro. The Complete Reversal AU is an attempt to create a universe where all the demon and slayer characters could switch places. Most of the canon characters end up being mostly similar to the originals but with changed roles to better suit their personalities. There are also a large cast of original characters to fill roles that were missing.