Gordian Warrior(1979)

Gordian Warrior is an animated series set in a post-apocalyptic Earth where survivors rebuild civilization across barren wastelands. Daigo Otaki, an orphan raised by his uncle, discovers as an adult that his father—a brilliant scientist—designed Victor City, now managed by Daigo's sister Saori. She urges Daigo to inherit his father's legacy: Gordian, a powerful super robot system. Daigo joins the Mechacon, an elite combat regiment tasked with protecting Victor City from the Madokuta organization. As he pilots Gordian, Daigo must master his inheritance while defending humanity's last stronghold against relentless attacks.