Siren Kny

this is the Au where the hashiras are higher-up sirens (I made that up) While the Kamaboko squad+Senjiro,Aoi is middle sirens, and the normal demon slayers are just normal sirens, Kagaya and Amane is the king and queen, demons are the mermaids (Yes I'm making Mermaids the villains) Uppermoons: Higher-up mermaids Lowermoons: middle mermaids normal demons: normal mermaids Muzan: the mermaid king story: When the hashiras met Tanjiro and Nezuko, Nezuko is a mermaid, the hashiras have swap personalities, Obanai: Mitsuri Mitsuri: Obanai Shinobu: Sanemi Sanemi: Shinobu Tengen: Muichiro Muichiro: Tengen Rengoku: Giyuu Giyuu: Rengoku Gyomei: Is just ruder