You fall in love with Chise first. Then you watch her become a weapon, and the show breaks your heart knowing she'd let it happen to save him. Every episode after that is about whether love can survive when one half of it stops being human, and Shuuji's desperate refusal to accept that it can't.

Shuuji and Chise are high school seniors in a small military town in Hokkaido, and their first romance is shy and clumsy, carried on partly through a diary they pass back and forth. That fragile happiness breaks apart when enemy planes suddenly bomb Sapporo while Shuuji is visiting the city with friends. Running from the devastation, he sees something he can never forget: Chise, with steel wings and a huge gun in place of her right arm, shooting down enemy fighters one after another. Without her consent, the frail girl he cares about has been turned into a cyborg weapon powerful enough to wipe out whole cities. As the fighting moves closer to home, her transformation puts heavy strain on their bond, and the two are left unsure whether she is still human. The drama sets tender, awkward romance against the growing dread of war.