A dismembered corpse of a naked woman was found on the riverbed at night. It soon turned out that the method of the case was very similar to the novel "Vexations" published in small copies 10 years ago. Investigator Kosaku Kurumiya's younger sister Reimi has a visual impairment. She has contributed to solving numerous bizarre cases by making full use of her sharpened sense and her reasoning power. Will she really get to the heart of an unprecedented case?