Gunslinger Girl story is about brainwashed girl who does not have relatives or places to go are being trained as professional assassins and given mechanical bodies by a nonprofit organization called welfare. They have lost their conscience and do not hesitate to kill at all. They spend their lives smoke stained, covered in gunpowder and blood.
This sad story about suffering girls who have lost their past but who still cling to life. After they are brainwashed, they can kill with a straight face and without hesitation. They did not think about their actions do not feel sorry for that. However, behind their cute disguises, they destroy themselves and refuse to grow up.