Jubei Yakyu, the protagonist, is pressured into joining the baseball team of the prison that he has been incarcerated in. The first opponents of he and his teammates are the all-female Black Dahlia team, who - to their surprise - begin skillfully murdering Jubei's partners left and right. The hero soon discovers that the main villainess and headmistress of his prison, Frau Ishihara, set up this game so that points are given not to how well they play the sport, but by how gruesomely the Black Dahlias are able to kill everyone on the opposing team.Jubei manages to escape the game by faking his death, and corners Ishihara, who then - in a last ditch effort - summons "GLOCKENHEIM"; a cybernetic monstrosity which uses Jubei's younger brother, Musashi, as its power source. As GLOCKENHEIM has been programmed to eliminate all he sees, however, he destroys the Black Dahlia girls by dropping out of the sky and crushing some of them, clubbing one with his spiked weapon, having an organic part of his body devour one alive, and then finally killing the lead girl by launching a round of exploding baseballs at her with his Gatling-style weapon.
The former crimes of some of the individual Black Dahlia team members consist of:
- Eliminating her entire school by poisoning lunches
- Decaptitating children and starting a collection with their heads
- Driving a stolen car into a village, setting it on fire and killing all within
- Bombing a commuter train which resulted in 100 fatalities
- Firing a home-made rocket into a tour boat and sinking it