"If the master commands it, I can even destroy mankind."

Counter-terrorism unit, and so forth, are a part of SORD, an organization established for the purpose of training operatives to defend the country against future threats. With nowhere to go, girls who have lost their places are sent to SORD, with guns in their hands. To earn forgiveness for existing, this is their only way.

In the SORD's specialist school, Mihama Academy, Class D, where Arata serves as a handler, is a gathering place for the misfits, nicknamed "Dead Stock". To help them survive as long as possible, Arata trains them using a neural connection technology called "PeTS".

And then one day, he encounters a mysterious girl. In a terrorist hideout, a girl named L, sleeping in a stasis tank. As if guided by fate, Arata connects with L, using PeTS, overcomes a desperate crisis, and welcomes her into his class.

However, this also marks the beginning of a fight against the mysterious terrorist organization Heidio.

Taking up arms, girls who have lost their places in the world, this is their story――

Windows version of the now-closed mobile game. In addition to chapters 1~4 from the original version, an entirely new fifth chapter will also be added, along with new scenarios for the girls in S group.