
Mobile Suit Gundam: Iron-Blooded Orphans: In Season 2, Tekkadan has gotten powerful enough to begin half-metal mining operations on Mars.But when Hell seized those robots, he drew the attention of the Mykene Empire - the ancient creators of the mecha that had been forced to live underground - and they decided to return to the surface quite violently (in the sequel, Great Mazinger). Hell hoped to find them and use them to further his goals. Mazinger Z: An archaeological expedition researching ancient ruins in the Greek Island of Bardos went too deep in the underground mazes of the island and found an army of Humongous Mecha.
