A novelist receives a letter from a female university student named Kubo about strange sounds that emanate from a room in her apartment. They begin to investigate incidents involving former residents, and eventually discover the shocking truths lurking inside the building.

For 60 years, the group of detectives known as "Detective Office 5" has raised the bar for detective work. The agents of Detective Office 5 are a group of stellar detectives lead by the genius code breaker Detective 507. When an unknown client enlists 507 to crack his most difficult programming code yet, the detective embarks for Shanghai where he crosses paths with a sniper, an informant, the head of the Blue-Dragon Mafia, and beautiful singer on the run, Meilan. As 507 stumbles deeper into a twisted quagmire of intrigue he discovers the sad truth behind the mystery.

In a Japan of the near future, the government program Plan 75 encourages senior citizens to be voluntarily euthanized to remedy a super-aged society. An elderly woman whose means of survival are vanishing, a pragmatic Plan 75 salesman, and a young Filipino laborer face choices of life and death.