Uchuu Koukyoushi Maetel: Ginga Tetsudou 999 Gaiden

Maetel left her home planet, La Metal, a frozen world where survival requires becoming a cyborg. She is called back as her options narrow: embrace her mother's fate by becoming a machine and losing her humanity, or join humans in opposing machines. She has allies who support her, including metallic beings seeking peace. By accepting their friendship and challenging those who define humanity solely by flesh, she might carve out her own way.