In the future of the Burst Angel setting, there are major crime problems in Tokyo, and it has become legal to possess firearms in Japan (this change is described as having been instituted partly due to an unusual rise in crime prior to the legalization, which lead to the gun control laws being repealed in order for lawful citizens to protect themselves). At the time of the storyline, the police force who were charged with protecting the citizens (known as R.A.P.T., as an acronym for 'Recently Armed Police Task force') has resorted to exterminating criminals rather than arresting them.