Victory Song For Tomorrow
Five thousand metres above ground, Dai-Guard and Kokubogar must brave the perils of the Heterodyne's body in search of the original fractal knot. But even as they battle their way through the numerous obstacles in front of them, the clock is ticking- in less than two hours, the army are going to launch a destructive OE that will take down not only the Heterodyne, but vaporise all of Tokyo as well! Will the two giant robots be able to pull off a victory in time?
Aired 28/03/2000EP 26 - Victory Song For Tomorrow

Dai-Guard
Thirteen years after their sudden disappearance, an alien race known as the Heterodyne resurface without warning. To combat the Heterodyne, three office workers from the 21st Century Security Corporation operate Dai-Guard - a giant robot no longer regarded as an oversized paperweight. Unfortunately, Dai-Guard is somewhat obsolete and in disrepair. It's a tough job, but salarymen can also save the world.
(Source: Anime News Network)