Jūrō Minami is a central protagonist in the original 1967 tokusatsu series. He is a young man and a highly capable operative for the international peacekeeping organization known as Unicorn, where he holds the designation of agent U3. His background is established during the series premiere, when both he and a young boy named Daisaku Kusama are shipwrecked and subsequently captured by the terrorist group Big Fire, also known as the BF Syndicate. It is during their escape from a secret enemy base that the pair discover the colossal robot that would become their greatest asset, with Minami playing a crucial role in the events that lead to Daisaku becoming the robot’s sole commander.

In terms of personality, Minami is defined by his enthusiasm and a hot-blooded nature, which makes him a dynamic and proactive agent. He is depicted as brave and dedicated to his mission, always placing himself in the line of danger alongside his young partner. While he can be somewhat buffoonish at times, this trait never undermines his effectiveness as an operative, and he consistently proves himself capable of getting the job done. His primary motivation is to thwart the global conquest plans of the interstellar tyrant Emperor Guillotine and his military forces. As a top agent of Unicorn, his duty is to protect the Earth from the monstrous creations and advanced weaponry deployed by Big Fire. Beyond his professional obligations, he is driven by a strong sense of personal responsibility and camaraderie, particularly concerning Daisaku.

Minami’s role in the story is multifaceted. He is first and foremost the senior field partner and protector of Daisaku Kusama, the only person who can control Giant Robo. He acts as a bridge between the boy and their superior, Chief Azuma, the head of Unicorn’s Japan branch. While Daisaku is the one who commands the giant robot in battle, Minami is the one who often handles the ground-level investigation, espionage, and direct combat against the agents and monsters of Big Fire, using his skills as an excellent marksman. He is an active participant in nearly every mission, frequently engaging in gunfights, piloting vehicles, and devising strategies alongside his colleagues.

Key relationships define his interactions throughout the series. His most significant relationship is with Daisaku Kusama, whom he treats not just as a partner but almost as a younger brother, offering guidance and friendship. He also works under the command of Chief Azuma, the leader of the Japanese branch, who assigns him his missions. He is a core member of the Unicorn team, cooperating with fellow agents such as Mari Hanamura and Mitsuko Nishino to foil Big Fire’s schemes. On the opposing side, he is a persistent and direct adversary of the BF Syndicate and its various leaders, including Emperor Guillotine and his regional commanders like Spider and Black Dia.

Minami does not undergo a dramatic personal transformation or character arc, as the series consists of self-contained episodes. However, his development is demonstrated through his growing bond with Daisaku and his increasing familiarity with the strengths and limitations of Giant Robo. He starts as a capable agent who happens to survive a shipwreck with a young boy and evolves into an integral part of a three-person team whose coordinated efforts—consisting of Minami’s field work, Daisaku’s command, and the robot’s immense power—are essential for victory. His most notable abilities include his proficiency with firearms, making him an excellent marksman. He is also a skilled field operative, adept at infiltration, reconnaissance, and hand-to-hand combat. Furthermore, he possesses a degree of technical knowledge and piloting skill, often flying aircraft or operating other vehicles to support Daisaku and engage the enemy.