Kyotaro Nishimura's Travel Mystery - Soya Honsen Murder Incident

While returning from a business trip to Hokkaido, Detective Kamei of the MPD greets a middle-aged traveler in the waiting room of Minami-Wakkanai Station but is ignored by him. On the limited express to Asahikawa, the same man happens to entrust Kamei with a floppy disk before dying.