A series of mysterious murders have occurred in the heart of Tokyo. No clue who the suspect or the next targets are. The only information from the dying message is that the next scene of the crime will be Hotel Coltesia Tokyo. A young detective Kosuke Nitta has been ordered to become an undercover agent as a hotel concierge. A female clerk Naomi Yamagishi will be his supervisor. Can the two solve the mystery, while suspicious customers come to the hotel repeatedly?