Set in a parallel rendition of the Meiji Age, a youth called Sakamoto Ryunosuke returns to Kyoto from Shanghai accompanied by his creature (youkai) Nekomaru. The statute dictates that for a youkai to coexist unhindered with humans, it must possess a strictly licensed status. Kidou Shinsengumi Co., Ltd. oversees the apprehension of unlicensed youkai, yet it clashes with the Tsubamegumi, who oppose the fresh regulation. Ultimately, Ryunosuke is revealed as the heir to the Shinsengumi proprietor in Kyoto.