A blood-soaked woman, clutching a child, stands on a barren moor. This is the image of the ubume of the title. This creature, or figment, who may or may not exist, but who haunts the narrative of this novel, is defined as the visible form of the regrets experienced by a woman who has died during childbirth.
Set in the Tokyo of 1952, the story begins with a lengthy discourse on the function of the brain, mind and consciousness, and with preliminary discussions on the nature of reality, living matter, consciousness, death, folklore and the occult. The account is related by Mr. Sekiguchi, a freelance journalist, but the central character of this strange and freakish tale is the bookshop owner Kyogokudo, a Shinto priest and intellectual who likes nothing better than to have a captive audience to whom he can espouse his theories.
Given to bouts of lengthy pontification, Kyogokudo turns out to actually have something original to contribute to the solving of the mystery. Despite his ministrations as a man of the cloth, he remains a rationalist with a deep appreciation of the supernatural, someone who can conclude that "religion is a scheme the brain came up with so it could have its way with the mind — a holy gambit, if you will."