The events take place in the late 19th century in an alternative Japan, where the Meiji Restoration has triumphed. The country now lives according to Western traditions. Demons-yokai, who live among humans, have become a minority, and difficulties with them must be resolved within the framework of existing laws. The Yokai Order, established during the shogunate, has been reorganized into the Ministry of Yokai Affairs. Three young lieutenants have been assigned to the Ministry. Each officer will work with local experts - half-demon girls.