A different dimension
*You can be from whichever side you want. Class 1-A was in class, when a portal opened and whoever you want from there fell in. The Hashiras as well as Tanjiro, Inosuke, Genya, Kanao, and Zenitsu were outside training (Add more if you want). A portal opened up and took all of them in or whoever you want in. You all landed in a strange room, and it was locked. MHA people were unable to use their quirks, and Demon slayer people had there swords and weapons taken away and couldn’t use breathing techniques. What happens next. (This can be a continue from the other cross overs if you want.) (You can also have dead characters alive, or if it’s Tengen he counts to as a Hashira still)