Rosario + Vampire

Failing your senior year at eighteen is bad enough; getting a mysterious invitation to enroll at Yokai Academy instead of repeating it is the kind of luck that shouldn't feel this suspicious.

The setup plays it straight for about a paragraph: your future's a dead end, then an unexplained acceptance letter shows up out of nowhere. Yokai Academy turns out to be less a fresh start and more a place where the female student body has teeth, claws, and considerably more control over the situation than a normal school would allow.

You navigate the academy and its residents from a male protagonist's perspective, moving through a school setting stitched together in a sandbox structure rather than a straight line, with the monster girls around you consistently running the show. The framing borrows enough from its source material to work as a parody without needing you to know the original.