Based on the horror game Ao Oni by noprops.

On the outskirts of town stands an abandoned house where ghosts are rumored to appear. Hiroshi and his classmates Takurou, Takeshi, and Mika pay the house a visit, only to be attacked by a bizarre monster, the Blue Devil. Will Hiroshi and his friends succeed in answering riddles and escaping the house, or are they doomed to live hilarious lives forever with the Blue Devil in the haunted house?! The courage-testing life of these four friends begins with the Blue Devil who continues to entertain even after death.

Aux abords de la ville se dresse un manoir que l’on dit hanté par un mystérieux monstre bleu (Aooni, en japonais). Hiroshi et ses camarades Takuro, Takeshi et Mika ont décidé de s’y rendre pour en avoir le cœur net.