A city of rain is gripped by innumerable unsolved mysteries, under the complete control of a megacorporation. Master Detectives from around the world, each possessing unique powers, must rise to the challenge of uncovering the truth. With Shinigami by his side, Yuma joins the investigation as a trainee of the detective agency. Travel freely within the fully 3D environment of the city to gather evidence and testimonies.

As the investigation progresses, a realm known as the Mystery Labyrinth will appear, creating a path toward the truth. Once inside however, the mysteries shrouding the case materialize as gimmicks and traps, lying in wait to consume Yuma. The rules of reality don't apply here: delve into the ever-changing Mystery Labyrinth and get to heart of the case.