A serial atrocious incident, commonly known as the "X-Day Incident," occurred in Shinjuku, which has become a dangerous city, and she works as a police officer. One night she is attacked by someone and is put in a poisonous collar because she is busily working for the safety of the community. Those who appear in front of the confused main character are men of dubious origin. They are said to be investigating atrocious cases on their own, since they belonged to a former police organization. They will start investigating with them without knowing whether they can be trusted. Who has her life? And will the day come when Shinjuku will be played back?