"Who put this collar on me?"
The protagonist is a policewoman who works in Shinjuku, which had become a dangerous city after a series of brutal incidents popularly referred to as the "X-Day Incident".
She had been busy working in her assigned area everyday in order to keep it safe. But one night, an unknown assailant attacked her and placed a collar built in with poison around her neck.
Amidst the chaos and right before the protagonist’s eyes were men with suspicious backgrounds. They’re all part of an organisation composed of former police officers and have taken it upon themselves to investigate the brutal cases.
Without knowing whether she should trust these men or not, she suddenly became the person who held the key to this massive case.
In order to remove the collar that places her at the edge of death and to liberate Shinjuku from the malice that binds it, she cooperates; beginning to investigate the incidents with the men.
Who holds her life in their hands? Will Shinjuku ever return to its former glory?
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