Gedo Gedo was the Monster of the Week on Ep.21 of the UFO Robot Grendizer and the 2nd Mecha Beast piloted personally by Blacki in the show. Gedo Gedo was a humanoid type Beast, green, purple and Dark Blue in color, with a light blue face. It's vehicle was the rare cigar shape UFO which comprise the whole body, with two antenna structures coming from the top part of the hull in the bow area (which in robot mode, is the lower forward of the Monster ... yeah: you come up with your own conclusions). Its sole abilities were strength and a laser beam coming from the antenna.

When the Vega invaders sent out a Sun reflecting Device to melt the Arctic Ice caps and cause worldwide flooding, Blacki took command piloted Gedo Gedo to protect it from Grendizer. As the weapon flies over orbit destroying the UN Radar base and causing disasters by melting the ice, Koji arrives on the site, and engages the Vega fleet, taking out many Minifos, but it been shutdown by the Blacki piloting Gedo Gedo. Duke arrives on Grendizer and engages the Beast, both taking the fight in robot modes.

The fight lasted for a few moments before Grendizer incapacitated its laser with Spin Saucer, and then finished off the monster with Screw Crusher Punch. The monster falls and Blacki abandons it on a escape pod before the explosion. Grendizer then rendezvous with the Spazer and finishes the Reflector with Space Thunder, hitting from the top of its hull.