Tanjiro's demon twin

You are tanjiro's twin sister your also a demon slayer but to be exact your a hashira when you became a demon your condition was strange you didn't need blood and couldn't die in sunlight you became one while sleeping at your estate thats also why you didnt know you were one till one of the other hashira's said ......

Read to know the rest also I haven't watched/read manga but if you have read my seven deadly sins story you will know why plot different