The focal point of the story is Ryōko Yakushiji, a 27-year-old ace detective of the Tokyo Metropolitan Police with exceptional skills. She often teams up with her apprentice Junichirō Izumida to investigate unusual and paranormal cases. Apart from dealing with earthly matters, Ryōko also has a history of confronting magical occurrences and is in a longstanding rivalry with another talented police investigator named Yukiko Muromachi.