In order to help her family, Tsugumi has agreed to marry a man of her father’s choosing whom she has never met. However, before this can happen, Tsugumi’s younger brother tries to commit suicide. The reason: he had in his possession a cursed book that has a strong emotional effect on whoever reads it. Tsugumi is then introduced to the Imperial Library Intelligence Asset Management Bureau, otherwise known as Fukurou, whose job it is to hunt down such cursed tomes.