The horror here isn't jump scares or gore. It's the feeling that something fundamental about the world is wrong, told through stories that sound like they could be real. Mukuroji's voice carries weight because he's describing things that shouldn't exist, and the show trusts you to sit with that dread instead of explaining it away. Bon and Koko aren't heroes solving a problem. They're kids trying to survive contact with something that leaves a mark just from knowing about it.

In this second season, a mysterious man called Mukuroji recounts ghost stories that no one has heard and that ought to stay unknown: the Nanashi Kaidan. A girl named Bon and a boy named Koko team up to seal away the supernatural. The five-episode ONA is a collection of short horror stories built around the uneasy sense children have that something is lurking out there in their everyday lives.