The Conscience Circuit is a special component in the Kikaider metaseries, a core plot element in the titular protagonist. The device is used as sci-fi commentary throughout the franchise on the nature of free will, morality, and a minor analysis of the Asimovian concepts of artificial intelligence.
The Conscience Circuit, also known as the Gemini System in the anime, is described to allow a robot to develop a sense of mortality to discern good from evil so to discern being manipulated by those like Professor Gill. However, Kikaider's Conscience Circuit is left incomplete and thus enables Jiro to possess free will to act beyond his programming (which differs in each series). However, as both the 70's series manga and anime showed, the Conscience Circuit doesn't appear to be everything for a robots sense of morality as there are times when Jiro actually harmed people (including innocent ones) out of self defense or rage. This could be the result of Jiro growing up and becoming more human.The downside to the incomplete Conscious Circuit is that Jiro is susceptible to the ultrasonic frequencies that compromise the melody produced by Professor Gill's flute.
In the manga and anime, while captured by SHADOW organization (Gill-Hakaider in the manga) an Obedience Circuit is installed into Jiro. While the Obedience Circuit was meant to make him a slave to Gill-Hakaider, it instead conflicted with the Conscience Circuit and made Jiro insane to the point of trying to take an innocent human's (Saburo Kazeda) life. Although Jiro stated that having both Circuits made him have a human heart, the Conscience Circuit itself was shown (in the manga and anime) to give Robots a heart (a righteous one) rather than absolute good. It was only later that Jiro managed to turn back to his old self with help from Inazuman.
It Is somewhat hinted in the tokusatsu that if a robot were to have a Conscience Circuit it would make them more powerful (although it could just be Jiro only). Gill himself stated that if Jiro were to gain a complete Conscience Circuit, Dark would have no chance at defeating him. Ichiro is also stated to be stronger than Jiro in terms of brute strength despite being less developed than him possibly due to his complete Conscience Circuit.
- The only media to present a complete Conscience Circuit is in the manga Kikaider 02 and Kikaider 01 (tokusatsu).