In the near future, a secret society called Dark Brain, led by the scientist Dr. Von Royenshtein, aims to dominate the Earth. Claiming to save the planet, they unilaterally decide to reduce the overpopulated Earth's population and declare war worldwide. The righteous organization Seigiman, trained for emergencies, rises to confront Dark Brain, igniting a fierce battle.
Amidst the conflict, Dark Brain's Eastern Commander and Dr. Royenshtein's daughter, Mizuchi, begins questioning the righteousness of the war. Simultaneously, Seigiman's member Seigi Blue, Doujouji Saki, starts feeling discomfort with their methods. Mizuchi, torn between loyalty to her father and doubts, falls into a trap set by Dark Brain's officer Naagaraaja, becoming a captive in Seigiman's secret base. Awaiting her are intense and perverse torments from the so-called "heroes of justice".
Meanwhile, Saki, who seemingly switched sides to Dark Brain, faces impending danger.