This not very enthusiastic review will look like a bad start to 2017; but I read this over a month ago, so for me it was more a bad end to 2016. 姑獲鳥の夏 (ubume no natsu, The Summer of the Ubume, 1994) by KYOUGOKU Natushiko (京極夏彦, born 1963) is part of a series centred on the monsters of Japanese folklore, in this case the ubume of the title, a baby destroying spirit created by a death in pregnancy, which has somehow become associated with a bird from Chinese folklore. The detective of the series is an expert on Japanese folklore and he lectures the narrator on this and other subjects intermittently throughout the book.
The narrator, who writes human interest stories for popular magazines, is investigating rumours surrounding a maternity hospital. The son in law of the chief doctor disappeared from a room that was locked on the inside a year and a half ago; and since then his wife's pregnancy has continued despite being long overdue. He discusses the case with his friend KYOUGOKUDOU (京極堂), who takes his name from the used bookshop he runs alongside his second profession as proprietor of a Japanese shrine. Kyougokudou convinces the narrator, by means of destroying his whole conception of himself and the world in a Socratic style interrogation, that such a story should be left alone, but discovering that the missing son in law was a former university friend of the two, he sends the narrator to consult with yet another student friend, telepathically gifted private detective ENOKIZU (榎木津).
By a strange chance, the older daughter of the family at the centre of the mystery has come to consult Enokizu; and soon narrator and various supporting characters are investigating the case. It becomes clear that the narrator himself has some buried memory related to the roots of the tragedy from the days when the son in law first met his future wife. And the rumours surrounding the hospital turn out to be even worse than those we had heard, with suggestions that one of the family's daughters has been stealing and killing the newborn babies of the patients.
I don't think the book has any interest as a puzzle detective story. The locked room mystery has special circumstances which leave a more or less limitless field of possible explanations. For some the attractions of the book may lie in its long conversations philosophising on the basis of amazing facts from popular science (which is sometimes about as scientific as you'd expect these kinds of thing to be) and expounding on Japanese folklore. These are at least bland reading, though they did not feel like a good use of my time. (The oddity of the narrator being so unsettled by this chatter is perhaps lessened by the book's setting in the early fifties.) For others the grotesque horror is presumably the selling point. I strongly disliked this. It reminded me of the forced charnel house horror that John Dickson Carr indulged in some of his weaker books (such as Hag's Nook), but bringing the same approach to pregnancy and childbirth. Now capital punishment or seventeenth century epidemics or whatever Carr might choose are far enough from most readers' lives that he can reasonably fool around with them for our entertainment; but that's not really the case here.
Most people who've read the book seem to have a high opinion of it (and it was 23rd in the 2012 Touzai Mystery Best list of Japanese mysteries), so I'm on my own in this. You can read a more generous review of the book on Ho-Ling's blog here; and you can make your own opinion, even if you can't read Japanese, because (for once) there is an English translation available, by Alexander O. Smith (Vertical, 2009).