Dr. Komyoji creates Jiro (Kikaider) but an explosion occurs. When Dr Komyoji's kids, Mitsuko and Masaru, their father was nowhere to be found. Jiro wandering aimlessly in a remote area eventually meets Mitsuko. Mitsuko teaches Jiro to go into his robot form and about the GEMINI system inside him. The two grow closer together but the relationship development halts when a mysterious flute playing causes Jiro to attack Mitsuko, which causes her to believing he is a mad machine. Jiro inevitably leaves Mitsuko and Masaru in fear of being destroyed. Mitsuko then hires Hanpei Hattori and his apprentice Etsuko Sarutobi to find Jiro and bring him home. Throughout the story, Jiro encounters robots and learns more about Professor Gill and the evil organization DARK. A reoccurring android named Hakaider causes Jiro out of control by whistling (similar to Gill's flute). The more Mitsuko encounters Jiro the more she falls in love with him. When Mitsuko and Jiro reunite, they search for Mistuko's mother who reveals to be in love with professor Gill but could not bare the pain of being away from her children and gives them the location to Professor Gill's headquarters right before she killed herself. After they discover the location, Jiro attempts to fight Hakaider alone and also discovers the brain inside Hakaider's head is that of Professor Komyoji's. Professor Komyoji overtakes Hakaider's body before Hakaider could destroy it and infiltrates the headquarters. Once Professor Gill discovers Dr. Komyoji is in control he sends his robots to attack them. Jiro was able to give the brain to Hanpei in order to put it back into Dr.Komyoji's body. Professor Gill attempts to control Jiro with his flute, but Jiro to is able to overcome it. Hakaider then attempts to kill Professor Gill for betraying him and destroys the place along with Gill. Hanpei, Mitsuko and Etsuko able to escape, but didn't see Jiro escape with them. In the end, Mitsuko has hope that Jiro will return to them.