Sigma Circular

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The , referring to itself as , was a sentient machine that Gold Drive and Roidmude 004 created in order to dominate all of humanity.
==History==
During the first attempt to activate this machine, Medic was originally meant to be a sacrificial vessel, but Brain takes her place to save her from brainwashing and sacrifices himself instead. 
After his escaping, Gold Drive and the Reaper Legion infiltrated the Special Defense Center headquarters, and placed Sigma under evolution process before the Kamen Riders (and later joined by the now-defected Roidmude generals Heart and Medic) would stop him from his plan on occurring the second Global Freeze. 
Sigma's evolution was completed and activates the second Global Freeze just before Drive and Heart arrived to stop the machine. Sigma was destroyed by the combining finisher attacks of Drive Type Tridoron's Rider Kick and Heart Over Evolved's strength punch. With its destruction, the Global Freeze ends and all humans who were transformed into data were returned to normal. 
==Forms==
==Behind the Scenes==
===Portrayal===
Sigma Circular was co-voiced by , and Masakazu Morita (who also portrays Tenjuro Banno).
===Concept Art===
Sigma Circular designed by .
==Notes==
*If the word "Sigma" were changed to the Greek letter ∑, its name ∑-Circular would resemble that of Mashin Chaser's E-Circular weapon.
*The giant teeth-like structures generated by the Sigma Circular have been seen in the show's opening since the very first episode.
==Appearances==
* Kamen Rider Drive
**Episode 44: Who Loves Heart the Most?
**Episode 45: What is a Roidmude's Last Dream?
**Episode 46: Why Must They Fight?
**Episode 47: Who Will You Entrust the Future to, My Friend?
==Navigation==
Category:Villain Weapons
Category:Mecha
Category:Robot Monsters
Category:Final Villain
Category:Drive Characters
Category:Deceased