Professor Shigeru Kokudō is a dedicated researcher focused on artifacts from super-ancient space civilizations. He first meets Kuga Kudō in Britain during Episode 23, where he is temporarily stranded with his assistant, Autobahn. Kokudō prioritizes his archaeological pursuits above everything, including personal well-being, and exhibits profound self-confidence in his work.

He possesses an alternate state known as "Super Kokudou," triggered by removing his glasses, which boosts his brain's processing power tenfold. However, overusing this state forces him into a barbaric condition to cool his overheated mind. His research centers on proving the existence of a "super-super-ancient space civilization" predating all known super-ancient civilizations. Kokudō believes this precursor civilization held advanced technological secrets capable of unlocking ultimate power to save Earth, a theory heavily ridiculed at academic conferences. His studies further suggest all documented super-ancient space civilizations, except the hypothesized super-super-ancient one, experienced sudden extinction due to an unidentified cause.

While traveling globally with the Earth Granner team, Kokudō continues investigating these ancient civilizations. He is revealed as the creator of Gao Granner Tyranno. His unwavering goal is to discover the lost technology of the super-super-ancient civilization and harness its power to protect Earth.

His relationship with assistant Autobahn remains strictly professional, though Kokudō expresses appreciation for Autobahn's support in their research.