Noriyuki Inou is a bright and promising young officer for the JSDF Investigation Division. Among his peers, he is considered especially capable - an expert combatant and highly intelligent operative, though quiet and brooding. His talent is noticed by Hiroaki Nakagou, Chief of the Special Branch for the Tokyo Met Police, and is scouted to join. On his way to meet his sister in Shinjuku for dinner, Inou must run to save her as chaos descends on Shinjuku and it becomes engulfed in explosions and death. What kind of organisation is "Ultra Red"? What is their goal? We follow Inou as he seeks out those responsible for the death of his sister with a burning desire for revenge.