Kamir Santin is an Indian exchange student arriving in Japan who becomes entangled with the Prefectural Earth Defense Force. After a traffic accident, Dr. Inoue subjects him to unauthorized surgery at Hazama Medical University Hospital, forcibly transforming him into an 8,000-horsepower cyborg equipped with built-in weaponry, including shoulder-mounted missiles. Santin escapes the hospital but collapses, discovered and sheltered by math teacher Toshiyuki Roberi. Consumed by intense resentment over his cybernetic conversion, Santin initially blames the Telephone Pole Group for his condition. This fury triggers destructive outbursts, such as demolishing Roberi's apartment building with missiles upon encountering the group's agents.

Santin reluctantly cooperates with the Defense Force, though his volatile emotions frequently cause unintended weapon discharges. While his combat abilities prove valuable against the Telephone Pole Group, his lack of control complicates missions. The group forces Dr. Inoue to create a second cyborg, Yuko Inoue (Dr. Inoue's daughter). Santin initially refuses to fight her, citing his aversion to battling women, but external radio control forces his missiles to engage. He eventually retaliates independently after Yuko's relentless attacks, leading to a mutually exhausting stalemate.

The shared trauma of their involuntary cyberization fosters a deep connection between Santin and Yuko. Both express distress over their artificial enhancements, particularly Yuko's despair over her perceived loss of humanity and marriage prospects. Santin empathizes with her anguish. Their bond evolves into a romantic relationship. United by their desire to reclaim normal lives, they seek Dr. Mafune's assistance to reverse their cybernetic modifications.