Hikaru, the Chairman of the Intra School Organization

At a school built specifically to hunt monsters, three girls train in the deadly art of taking down supernatural threats. Yuki, Seira, and Hikaru — the student council president — actually pull it off early on, taking down a powerful creature named Varmus. But that victory falls apart fast when a new threat resurrects Varmus and starts picking off the people around them, starting with their teacher Kotone. The setup has a dark, pulpy energy to it: monster-hunting academy, a villain with a deeply unsettling agenda, and heroines who go from hunters to hunted in short order. This is a single-episode OVA from Studio Eromatick based on a visual novel, so it moves quickly and leans hard into its hentai genre roots without much buildup. The character designs are distinct and the animation holds up for what it is. If you've seen something like Bible Black or Discipline: The Record of a Crusade and you're into dark fantasy hentai with an actual threat driving the plot rather than just disconnected scenes, this fits that space. It is not a slow burn — the tone gets grim almost immediately and the monster-breeding premise is not subtle about where things are going. Worth a look if that specific mix of monster-hunter action and dark adult content sounds like your thing.