Brain is the world's greatest computer, and also the most intelligent being on planet Earth. One day, Brain decides to abandon its terrestrial moorings, and it's up to The Defenders to track it down. Unfortunately, Brain has developed an amazing army of deadly giant robots, including one with a huge "17" emblazoned on its chest-plate, with which it plans to subjugate its creators. A young boy whose family was killed by Brain's followers manages to activate Daitetsujin 17, which thereafter comes to his rescue whenever he is in danger from Brain's minions.
Professor Gill has created a machine that lets him restore destroyed robots. This machine is used to recreate all of the destructroids that had been destroyed by Kikaider. Kikaider is forced to destroy them all once again, and a new Destructoid Multi-Colored Sand Lizard.