Gunslinger Girl, Volume 2 — Kiyohiko Azuma

In Italy, select teenage girls have been transformed into cyborgs and subjected to a brainwashing process known as "Conditioning." These girls are then paired with fully human supervisors, called Handlers, and are made to carry out assassinations on behalf of a shadowy government agency. The girls are fiercely loyal to their Handlers and would do anything to protect them.