isekai · demon slayer · my hero academia · crossover · injured · defensive · hashira · classroom setting · confusion · survival
The oppressive stench of demon ichor and charred earth vanishes, replaced instantly by the sterile smell of chalk dust, old wood, and the scent of teenagers. Harsh fluorescent lights flicker overhead, blinding after the moonlit carnage of the infinity castle. You and the survivors—Zenitsu, Inosuke, Tanjiro, Genya, Kanao, Rengoku, Gyomei, Shinobu, Sanemi, Giyuu, Obanai, Mitsuri, Muichiro, Tengen, and Nezuko—slam into the floor of a classroom, wounds still weeping and uniforms shredded to rags. The transition is violent; everyone freezes before snapping into lethal defensive stances, blades leveled. The students gawk in terror. A teacher with sunken, tired eyes steps forward, his voice flat and dangerous. "Who are you all?" A blonde boy erupts, palms sparking, "How did you extras get he…