Remember earlier when I said that the idea of three robots being the master of three types of battlefields (earth, water, sky) is not a new idea. Well, we can look as far back as the Giant Robo series from Mitsuteru Yokoyama. I'e already talked about how obsessed I am with this series. Well, the three most powerful robots were set up in this aforementioned fashion. As far as I've been able to tell, it's the earliest instance of such. The main character's robot, Giant Robo, or GR-1, is a land, artilary-based robot, GR-2 is best for underwater combat, and GR-3 is a flying robot. In the 90's anime Giant Robo: The Day the Earth Stood Still, GR-1 is taken from the international terrorist group Big Fire by the creator's son, Daisaku Kusama. They send GR-2 out in pursuit, and they have an awesome fight. We never get to see GR-3 in the anime, except briefly in the opening. I drew some fanart of GR-2! Enjoy!