This one is really different from Mr. Mitsuda's other novels about urban legends, crime mystery, Japanese folklore/demon lore and anthropology. Plus it's quite a thick book, I admit I skimmed through most of the book. Although the historical background of the post-WWII Japanese society and the community of miners are interesting and refreshing--I don't remember the last time there is a Japanese novelist taking on the post-war society and the exploitation of the Korean slave-labors before, during and after WWII at the same time.
However the characters aren't very interesting, the story and the plot twists are decent and I'm satisfied with the explanation of the mysteries of the 'Black Fox', miners missing inside the mine when there is only one exit back to safety (ah la la 'locked room' mystery again ) and the death of a few miners who had a dark past of abusing slave-labors during WWII.
I'm not saying it isn't a book written with good research and effort, still it doesn't have the same spooky effect which I enjoy so much with the other Mitsuda's books.