Kyotaro Nishimura's signature travel-mystery series. Inspector Shozo Totsugawa of the Tokyo Metropolitan Police, often with Detective Kamei, investigates cases built around railways, tourist sites, regional cities, and timetable puzzles. For the fourth Yoshikawa Eiji Bunko Award, the prize recognized the continuing paperback series across multiple publishers.

This was not an award for a single volume, but for a long-running paperback series that continually joined travel atmosphere with detection.