During the Westernization of an alternate Japan, humans and spirits coexist. However, some spirits have been causing trouble, and the Ministry of Spirit Affairs is established to maintain harmony. Lieutenants Kei Agemaki, Riken Yoshinokazura, and Ganryu Hanakiri are chosen to represent the humans. They are introduced to their female half-spirit partners: Zakuro, Susukihotaru, and twins Bonbori and Hozuki, respectively. While Susukihotaru, Bonbori, and Hozuki are delighted, Zakuro is disgusted with humans and their acceptance of Jesuit ideas...