The original is the drama of "Yokoyama bright".

When you produce the animation, the director is made to cast a lot of character from Yokoyama original comics.

In that regard it differs significantly from the original.

Akakage, Three Kingdoms, Water Margin. Many well-known characters are out.

The idea was the 26 episodes, but only six episodes have not been produced.

https://en.wikipedia.org/wiki/Giant_Robo_(OVA)