SaiKano: She, The Ultimate Weapon

Chise is a schoolgirl living in a small military town in Hokkaido with her childhood friend Shuuji. Their lives are marked by everyday routines, with a focus on social relationships and minor concerns like the climb up "Hell Hill." However, their world is shattered by a massive air raid in Sapporo, which kills thousands and marks the beginning of a war. Chise is transformed into a cyborg, equipped with steel wings and a massive gun, rendering her the ultimate military weapon.