Saikano - Shin Takahashi

Hoping to introduce a little bit of normalcy into their lives, Chise and her boyfriend, Shuji, flee their wartorn hometown. Hiding out in a small, out-of-the way village, the two lovebirds start living together in domestic bliss. The couple's newfound happiness is short-lived, however. It becomes obvious pretty quickly that the fragile teenager cannot run away from her martial responsibilities. Much to Chise's horror, her body has transformed into a weapon of mass destruction--and like it or not, she must fulfill her duty to kill.