in this story Muzan is still a demon king but he is a demon slayer witch he is only killing he's weak demons and Tanjiro family is still dead with nezuko... but what if Muzan adopt Tanjiro as his Brother... and Tanjiro Accept it?.... let's fine out! ^°The cover is not mine! °^ also Tanjiro is going to be a girl and there will be a harem... kinda I guess?