Y? Amagi is a slightly eccentric detective who has been assigned to the Twelfth Section of the Tokyo Metropolitan Police Department's First Investigative Division from the Lost and Found Centre. The Twelfth Section is called the "graveyard of detectives" and ridiculed as the "banishment room where hardened detectives who cannot be fired are sent." Its assembled detectives K?suke Samura, Takumi Yamashita, Keita Nagasawa, Tamaki Mizuta, and Masatoshi Katagiri are elite and yet oddballs. Amagi appears fixated with time which seems to have no relation with a case. Raising questions about the timelines of the perpetrator and victim derived from the estimated time of death, time of crime, time of alibi, and time limit, he searches for the meaning of "blank time" which arises from this. He obsesses over the weight of every minute and second of time because of some incident.