Mahou Shoujo Kokone wa Kakukatariki

Kokone decides to become a magical girl to save Hoshi Karen, the one who protected her even while tanks pursued her. After meeting Karen, Kokone is entrusted with her Grimoire and sets out to follow in her footsteps. In this world, magical girls are regarded as a “calamity.” Kokone chooses to become one anyway, beginning her own story as she tries to save the girl who once protected her.