An obsessive-compulsive Japanese librarian living in Bangkok spends most of his days contemplating suicide in his apartment. His life changes when he witnesses the death of a young girl and becomes acquainted with her elder sister.

Seven-year-old Rio visits her grandparents in Japan for the first time. She observes the beauty and unfamiliarity of the household, sensing a distance between her American family and the Japanese relatives. When her mother, Seiko, reveals an open secret during tea, the children are excused from the room and something happens behind closed doors.

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. The floppy contains his investigative notes on a murder that happened two years ago...