SORD — Social Ops, Research and Development — recruits talented operatives for anti-terrorism training. All kinds of misfit girls are enlisted at its schools and handed live firearms in the name of national defense. Arata is the handler of Class D at Mihama Academy, a school for SORD operatives. Class D is called Dead Stock because it is full of third-rate students. To improve his students' chances of survival, Arata trains them using PeTS, an experimental neural sync technology. On one extrajudicial mission, he finds a mysterious girl asleep inside an incubator at a terrorist hideout. She introduces herself as L, and Arata welcomes her into Class D. This triggers the beginning of Class D's fight against the mysterious terrorist organization Hadeo.