In a futuristic setting, the “ARK Project” has launched an initiative aimed at enhancing human life quality by employing robots for peaceful purposes. Leading the project, Dr. Komyoji has pioneered a method to endow a robot with a metaphorical human “heart” by integrating a “conscience circuit.” However, his work faces fierce opposition from fellow researcher Gilbert Kanzaki. Following Dr. Komyoji’s untimely death in what seems to be an accident, his children, Masaru and Mitsuko, become targets of enigmatic forces within the ARK Project, eager to seize the scientist’s research. Standing against these adversaries is Jiro, an android equipped with a human conscience, who champions justice under the guise of the hero Kikaider.