Four isekai protagonists get dumped into a world that's designed to mock everything they think they know. The comedy doesn't come from explaining the in-jokes to newcomers, it lives in watching Kazuma, Subaru, Tanya, and Lich King stare at echoes of themselves and have no idea what's happening. The movie knows you've watched all four shows, and it's built entirely around that, which means if you haven't, you're locked out on purpose.
Four separate worlds collide when a homeroom class tumbles through a dimensional rift into an unfamiliar realm. What they find is a wasteland terrorized by a massive magical automaton, and the locals who inhabit it seem disturbingly familiar. A girl-type golem speaks in Megumin's distinctive cadence. A woman commands respect in Tanya's military regalia. A mysterious man with a cane recognizes Subaru on sight. These aren't the characters they know, but they're close enough to cause serious confusion. Stranded together, the class has to figure out what connects these doppelgangers to their friends while surviving an immediate threat. The automaton won't wait for explanations. Neither will the strange politics of this broken world. Comedy erupts as the students navigate cultural clashes and mistaken identities while racing against time. It's a chaotic mashup of comedy and action that plays with the absurdity of multiple overlapping worlds and the question of who you'd be if circumstances were just slightly different. Expect creative collisions between different franchise sensibilities colliding head-on.