Zen Seizaki, a conscientious public prosecutor of the Tokyo District Public Prosecutors Office, works in Tokyo's newly founded Shiniki district. Zen and his associate officer, Atsuhiko Fumio, were assigned to a case involving deceptive advertising, and they investigated Japan Supiri, a pharmaceutical business that had produced faked clinical studies on the company's new medicine. The investigation takes a dark turn when Zen discovers a page stained with a mixture of blood, hair, and skin, as well as the letter "F" scribbled across the sheet, while studying the file of Shin Inaba, an anesthesiologist linked to the crime. As he digs deeper into the case, it expands beyond Zen's wildest imagining, challenging his sense of fairness and knowledge of the truth.