It turns homework into a countdown. Ao Oni The Animation walks away from the mansion escape loop of the original RPG Maker game and drops five folklore research club kids into a suburban town backed up against mountain forest, where the local legend suddenly has paperwork behind it: a former member's research notes, forty years old, surfacing while everyone is still arguing about culture festival ideas. That is the smart move, because dread that arrives through a filing box beats dread that arrives through a scream. Then the thing itself shows up, that swollen bald head and pinprick face that the internet spent a decade turning into a punchline, played completely, humorlessly straight. What sticks is watching five kids realize their club project stopped being a project.

Five members of a high school folklore club stumble onto something they should have left alone while preparing for their school's culture festival. Among research notes a club member gathered 40 years ago, they find a local legend that closely resembles "Ao Oni," a popular free horror game, and they pick it as their festival theme. They manage to contact the game's creator, but he dies mysteriously soon afterward. Suspicious, the club begins investigating on their own and uncovers a secret underground prison beneath the school. Then the fire doors lock, and the group finds itself trapped inside the building. Horror and mystery shape this film, which tells a new story based on the game.