Before Chise became the "ultimate weapon," there was another—Lieutenant Mizuki. A battle-hardened military woman, she volunteered for an experimental procedure after injuries left her unable to return to the battlefield. As the prototype ultimate weapon, Lieutenant Mizuki was highly successful on the battlefield, however, as the first candidate, her development was limited. When a more suitable candidate to become the weapon, Chise, is forced into the military, Lieutenant Mizuki thinks that she is silly, weak, and unsuited for the role. As the only other person to have undergone the procedure, however, Lieutenant Mizuki can hear Chise's thoughts and is the only one who understands her. As the war rages on and Chise's development progresses, Lieutenant Mizuki discovers more about Chise, ultimate weapons, and herself. Shuji and Chise are two Hokkaido high school students barely starting a relationship with each other. Then, with no warning, a squadron of bombers from an unknown country destroy the city of Sapporo. All hope is lost when suddenly, the bombers are destroyed by a small red light floating across the sky. At this point, Shuji finds out that the one responsible for eliminating the enemy forces is Chise, who reveals herself as a cyborg engineered for mass-destruction.
