This anthology-style mystery series is part of the D‑5 PROJECT, centered around Detective Office 5 - a long-running private detective agency in Kawasaki. Each detective is known only by a number rather than a name (e.g., Detective 596, 532), with standalone stories featuring different characters and surreal, quirky cases.

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.

Satoru is a fledgling writer. When his latest manuscript is rejected, his editor, recognizing his talent, offers him a cottage by the beach to work in peace. At first, he struggles, but he is driven to write after meeting a girl, Yoriko, on the beach.