The plot features many characters, both historical and fictional. Most of the narrative revolves around the cryptohistorical actions of Yasunori Katō, a mysterious former lieutenant of the Imperial Japanese Army who is himself a vengeful oni; a descendant of the people who rebelled against the Japanese Empire in ancient times. With an incredible knowledge of the supernatural and allies in China, Korea and Taiwan; Katō dedicates his life to crippling Tokyo, the seat of power of the modern Japanese Empire. His ruinous ambitions bring him into conflict with some of 20th century Japan's greatest minds including industrialist Eiichi Shibusawa, onmyoji Abe no Seimei's descendant Yasumasa Hirai, authors Koda Rohan and Izumi Kyoka; physicist Torahiko Terada, and author Yukio Mishima. The resulting conflict, involving science, magic and politics; spans 90 years of Japan's history.