The serial killer that the main character discusses with his class is Robert Hansen. He would kidnap prostitutes and take them in his plane into the forest where he would hunt them down and kill them. He lived in Alaska.
In several shots inside of Nishino's house, a video of a jellyfish is shown playing on his television. The jellyfish was a central theme of one of Kiyoshi Kurosawa's previous films, Jellyfish (2002).
The Takekura husband and wife family have moved to a city called Inagi city which is in west Tokyo, bordering Kawasaki city. The train line is the Keio (Sagamihara) Line.The unsolved murders took place in Hino city which is also a city in west Tokyo. Both cities are basically bed towns.