Jin Daiba is an ace detective in the First Investigation Division at the Tokyo Metropolitan Police Department. He is an enthusiastic detective and full of justice, but he holds a secret. His secret is that he killed a man who abducted and killed young girls. Jin Daiba did this because the law wouldn't punish him. The man held a high ranking position in the National Police Agency. Jin Daiba's secret is then uncovered by Assistant Commissioner Saimon Hirayasu, who leads a special investigation team for unsolved cases. Saimon Hirayasu transfers Jin Daiba to his special investigation team. Because of his secret, Jin Daiba must follow Saimon Hirayasu's orders to get rid of criminals secretly who the police are unable to punish. While digging into an unsolved case, they face off against a powerful organization.