The No. 4 Mobile Investigation Unit was quickly pieced together as part of reform efforts to overhaul the police organization. There, a wild maverick of a cop, Ibuki, gets paired with a serenely composed partner, Shima. Their role is to be on call 24 hours to fill in gaps in police shifts by investigative Units 1 to 3, to be the first investigators on crime scene and to risk their lives for a perfect criminal apprehension rate. In an increasingly morally relativistic world, questions such as "What is real justice" are posed in thrillingly fast-paced and comical whodunit fare with each episode a complete story.