Gekigangar III is a "sub-anime" of the anime series Martian Successor Nadesico that plays a critical part in the plot thereof. Initially, only Gai Daigoji and Akito Tenkawa are depicted as enjoying the series. After Gai's death, then Hikaru becomes the other resident anime fanatic.

As Nadesico progresses, we find that the very reason the Jovians (who are really humans) are attacking Earth is because they believe their cause to be just and they idolize the Gekigangar anime series. Toward the end, even Captain Yurika is a Gekigangar otaku. In the end, the Gekigangar series becomes a lesson on why people should not let anime become their moral code.

The various Gekigangar clips that were shown throughout the Nadesico series were later compiled together into an OVA.

The title, Gekigangar is a parody name with Gekiga and "-er" combined meaning "people of/from serious manga".