gridman sigma

Gridman Sigma was the proposed ally of Gridman in a sequel series that was never completed or even aired. Sigma would have become the alter ego of Toudou Takeshi, a reformed antagonist of the original series. Sigma would have fought a relative of Kahn Digifier.

In 2015, Gridman Sigma made his first public appearance in the anime short, Denkou Choujin Gridman: boys invent great hero where he is finally partnered with Toudou Takeshi.