 The evil Dark Demolition Corps led by Professor Gill has captured Professor Komyouji and his daughter Mitsuko, forcing them to build destructive robot monsters such as Grey Rhino King, Green Mantis, Orange Ant, Blue Buffalo, etc. But to stop their dastardly plan, Professor Komyouji built the guitar-playing android Jiroo (in honor of his late older son Tarou), which transforms into the super-robot Kikaider to fight the monsters Dark sends out. However, Komyouji and his android are discovered by Gill. Jiroo fights with Gill s Android-Men henchmen, causing Komyouji s lab to burn down. Komyouji orders Jiroo and Mitsuko to escape, but he is lost in the inferno... Each week, Jiroo/Kikaider wanders around Japan fighting the robot monsters Gill sends after him, while looking after Mitsuko and her little brother Masaru, who are still looking for their father. Later in the series, an evil black Kikaider-like android enters the fray. Created by Professor Gill, he is the destructive cyborg Hakaider, created to destroy Kikaider. Implanted with a human brain and armed with deadly weapons, Hakaider also has a dark secret, much to the shock of Jiroo and his companions...