Isaku: Respect

A note appears in Kotomi's bedroom that knows things about her it absolutely should not know. Personal things. The kind of details that make you feel watched. The note gives her instructions: go to the old school building. She goes, because what else do you do when someone has leverage over you, and finds that her classmates got the same treatment. Then the doors lock, and people start disappearing. That is where this 3-episode OVA from Production D.M.H gets genuinely unsettling. The abandoned school setting does a lot of heavy lifting here — there is something about empty hallways and flickering lights that the source visual novel understood well, and the adaptation carries that dread into every scene. The character dynamics between Kotomi and the more assertive Miyuki give it some grounding before things spiral. If you have watched Bible Black or Discipline: The Record of a Crusade and appreciated when hentai actually commits to building tension before the chaos, this sits in that same space. It is closer to horror-mystery than anything else, using the trapped-in-a-building premise the way a decent thriller would. The explicit content is there, but the setup earns more attention than most entries in the genre bother with. Short runtime, eerie atmosphere, and a premise that actually has stakes. Worth a watch if that combination appeals to you.