Carrie, the main character, is a Gun Girl, a member of a group of young women who fight with outdated firearms. She suffers from amnesia, unable to recall her combat experiences, and is struggling to find her place in a world on the brink of collapse. By 2030, a global war has ravaged the planet, wiping out half of the world's population and rendering traditional warfare obsolete, with advanced technologies like satellite lasers and intelligent AI taking center stage. The Gun Girls represent a nostalgic and unconventional approach to combat.