Mononoke & Requiem From The Darkness have set the bar so high for folkloric horror that shows like Mouryou no Hako simply aren’t good enough anymore.
In terms of the story, it’s perfectly fine. However, this is a cartoon, and you need to bring more to the game than just a spooky story. The horror element needs to come through visually and this is where the show fails. The set piece scenes work to a certain extent, they are creepy, if not dazzling. What it fails to do is create a mood throughout the show.
Mononoke was unrelenting in it’s creation of unease in the viewer. I know people who stopped watching because it was creeping them out. Requiem From The Darkness was a bit more Grand Guignol in it’s approach, but the art direction and character design brought out the unpleasantness of the characters and world in the stories. There is the sense that these interpretations could only exist as cartoons.
Take away the supernatural events, and this episode of Mouryou no Hako could easily pass for a high school drama like Maria-sama ga Miteru. This is a workmanlike adaptation, anime as a mechanism for translating a book to tv rather than a work that justifies its existance as animation. Even the novelty of CLAMP character designs is smothered by Asako Nishida’s pedestrian interpretation of them.
As a way to simply enjoy the story, this is fine. And considering the novel isn’t available in English that’s a decent enough reason to watch. However, as a work of animation it’s a big disappointment.