Johnny Sokko, known in the original Japanese version as Daisaku Kusama, is a young boy who becomes an unlikely hero when he is thrust into a global conflict against the alien terrorist organization known as the Gargoyle Gang, or Big Fire. Portrayed as an ordinary and inquisitive child, his life changes forever after a shipwreck strands him on a secret island base. On this island, he and a secret agent named Jerry Mano discover a giant robot being constructed by a captive scientist named Dr. Guardian. As the scientist attempts to destroy his creation to keep it from the enemy, the resulting explosion activates the robot. The device that controls Giant Robo is a wristwatch communicator, and because Johnny is the first person to speak into it after its activation, the robot’s electronic brain is programmed to obey only his commands.

As a character, Johnny is defined by his courage and sense of responsibility. Despite his youth, he willingly accepts the immense burden of controlling the most powerful weapon on Earth. He is recruited by the international peacekeeping organization Unicorn and given the code number U7, becoming the group’s only child member. His personality balances the typical traits of a boy his age—such as playing with friends and attending school—with the serious duties of an agent who regularly faces down giant monsters and enemy spies. He is resourceful and brave, often finding himself in dangerous situations alongside his partner, Jerry Mano, yet he never shies away from the call to action. His unwavering loyalty extends to his mechanical friend; he views Giant Robo not just as a machine, but as a partner and companion, expressing genuine distress when the robot is damaged or captured by the enemy.

Johnny’s role in the story is central, as he is the only person who can command Giant Robo. This makes him a prime target for the Gargoyle Gang, led by the alien Emperor Guillotine, who constantly schemes to steal Johnny’s wristwatch or capture the boy to gain control of the robot for their own plans of world conquest. While Unicorn agents like Jerry Mano and Chief Azuma provide tactical support and field assistance, the primary responsibility for defeating the giant monsters that attack Earth falls to Johnny and his robotic champion. His key relationships are built on trust and cooperation. Jerry Mano acts as his mentor and guardian, often accompanying him on missions and protecting him from enemy agents, while the rest of the Unicorn team treats him as a valued, if unusual, member of the organization.

Throughout the series, Johnny’s character develops from a boy who simply happened upon an incredible power into a seasoned and determined hero. He demonstrates growth in his ability to handle dangerous missions, think strategically under pressure, and face the emotional weight of his role. This development culminates in the final episode, when Emperor Guillotine reveals himself in a giant, atomic-powered form. As the villain threatens to destroy the Earth, Johnny must make the difficult decision to command his robot into a suicide mission. In a poignant conclusion, Giant Robo ignores Johnny’s desperate orders to retreat and carries the emperor into space, where both are vaporized in a tremendous explosion, leaving Johnny to sorrowfully salute his fallen friend.

Despite his small size, Johnny Sokko possesses notable abilities suited to his role. His primary and most significant ability is his control over Giant Robo via his two-way wristwatch communicator, which allows him to issue commands that the robot’s electronic brain cannot disobey. As an active Unicorn agent, he is also trained in the field, often using a standard-issue handgun in gunfights against the Gargoyle Gang’s soldiers. He is physically fit and agile, frequently engaging in chases and fights with enemy agents, and he consistently demonstrates quick thinking that helps him survive traps and interrogation scenarios that would challenge an adult operative.