Amagi Yu was working at the lost and found center of The Tokyo Metropolitan Police Department (MPD) when he was re-assigned to Division 12. Within the MPD, Division 12 is known as the dead-end to the career of all detectives. A place where no matter how glorious your past may have been, once you are sent there, you can forget about ever returning to the limelight again. However, the detectives in Division 12 are actually all excellent detectives, they just have their own idiosyncrasies and are tough to handle. Notwithstanding how their individual characters may clash with one another, they still work as a team to resolve all the tough cases assigned to them.