Tokyo, 2050. La présence de firmes étrangères amène chaos et corruption au cœur de la ville. Les quartiers de Shibuya, Roppongi et Akihabara deviennent rapidement des zones de non-droit où des milices équipées de mechas armés de gros calibres font la loi. Si la police ne semble pas leur faire peur, ils redoutent par contre un quatuor de jeunes femmes adeptes de « Gunfight » et d'explosions en tous genres. Toutefois, leurs motivations et leur façons d'opérer sont encore inconnues….
Meg goes undercover at an all girls academy where a secret society has conjured up the spirit of an ancient demon..
In Westland, New York, a murderer is indiscriminately killing people… A girl witnesses one of these murders, and the knife is turned on the helpless girl shaking with fear. Meg returns to this town with Joe to celebrate the "birthday" of Shirley, who used to live with Meg. Orphans, they had decided that the day they first met would be her birthday. In the past, Meg had taken care of three little children, including Shirley, just before meeting Joe. The children were then adopted by a police officer, Sam. He possessed a strong sense of justice and they are supposedly living happily together now. Meg and Joe happen to help a person and receive a reward. They buy a present for Shirley with the reward money and go to meet Sam. However, they notice him acting strangely. Upon questioning him, he explains that Shirley was assaulted by a murderer and seriously injured. Joe says to the grieving and angry Meg, "Let's exact revenge on the murderer for Shirley.".
