(from ebookjapan):

The year is 1993. Violent crime was on the rise, and the national police were powerless. The government adopted a policy of housing ex-convicts and unidentifiable persons in a category called "open zones. Five years later...

It became an "inferno city," an independent crime sub-nation where the strong live and the weak die. In a city where there is no discipline, no right or wrong, the battle for life and death now begins!