(I kept getting distracted from my mostly-weekly Invid's Guide post. Sometimes I think not being allowed to use the Internet would make it easier for me to blog. Then I say "...wait a minute...")
This giant robot dude here is inspired by and paying homage to a silly old Ultraman-like dude called Jumborg 9/Jumborg Ace (he kinda had two forms that he took depending on situations). So of course, he gets Jumborg's theme song attached to him a lot. (That's also Jumborg's transformation sequence at the beginning there. Bow in awe before the mind-bending retro.)
All I can really tell you beyond that is that Jumborg was an anniversary series, and also loosely connected to the legal dispute between a Thai company and Tsuburaya Productions which caused a lot of grief and some weirdness in Ultraman distribution (e.g., English DVD releases of the old Ultraman have some empty spots in their English soundtracks because they were licensed by the other company rather than Tsuburaya, and only Tsuburaya had access to the full audio for the English dub, and with the resolution of said dispute it sounds like said DVD release was rendered technically illegal). So... yeah. Kind of a messy thing.