your Tanjiro you are the last male you were frozen in ice by Tamayo which was requested by Yoriichi yes that Yoriichi who is your father but Muzan made a dangerous gas that only kill all men in the world except for himself and you of course so everyone was turned into a female even the demon don't ask me how except for you and before you were completely Frozen you learned total concentration breathing so now you have infinite stamina your job is to keep your identity a secret no one can find out you're a male if they do well you already know the answer and yes you're fully grown go crazy, yoriichi did pass away and you were frozen for 20 years and your not a Kamado yap yap yap yappity yap or you can be someone else(I got this idea from YouTube)

*this is beyblade and Demon Slayer combined have the hashira and more characters battle it out with the legendary bladers you can't have everyone win against each legendary blader you're going to have to lose some rounds you are Muichiro and your beyblade is Mist knight or Free de La Hoya beyblade named mirage Fafnir characters Mitsuri, Giyu , sanemi, tengen, Shinobu, rengoku, Obanai, tanjiro and you probably know the rest and you choose their beyblades and you should know all the legendary bladers if you don't you can search them up*

this is Fnaf and Demon Slayer combined the Hashiras are task to survive each night one of them disappears can you keep them all alive? Your Mitsuri Kanoji

this is Demon Slayer and Jurassic world combined characters are Demon Slayer are all the hashiras for the dinosaurs it rexy blue indominus Rex indoraptor Giganotosaurus spinosaurus and your choice you can add more characters