Hiyoshi Gō is the youngest of the three Gō brothers and a central member of the Voltes Team, piloting the Volt Frigate which forms the legs of the giant robot Voltes V. As a ten-year-old boy with brown hair and freckles, he is typically seen in a light green uniform marked with a yellow V insignia. His early life was profoundly shaped by the mysterious disappearance of his father, the brilliant scientist Kentaro Gō, who vanished on a diplomatic mission to the planet Boazania when Hiyoshi was very young. This loss left an emotional void, and despite being surrounded by his protective older brothers Kenichi and Daijiro, Hiyoshi grew up without the direct warmth and presence of his father, which at times leads his teammates to perceive him as somewhat naive.

From an exceptionally young age, Hiyoshi demonstrated a remarkable aptitude for mechanics, robotics, and electromagnetism, a prodigious talent recognized by university professors. His technical genius is one of his defining traits, and he is responsible for creating Tako-chan, a small, octopus-shaped assistant robot. While Tako-chan is initially dismissed or viewed with suspicion by some teammates, the little robot later proves its worth on critical missions. Hiyoshi’s interests extend beyond theoretical science; he is also a skilled swimmer and diver, abilities that not only prove useful for navigating deep-sea environments but also complement his role piloting the maritime-focused Volt Frigate. When the Boazanians invade Earth, his expertise secures him a dual role on the team: he serves both as a pilot and as the field technician responsible for handling vital repairs and maintenance on Voltes V during operations.

In terms of personality, Hiyoshi blends a cheerful disposition with an underlying resilience. Early in the series, his youth occasionally manifests as a lack of focus, such as when he prioritizes personal interests like boat racing over his duties, a behavior that causes friction with his older brother Kenichi. However, as the conflict intensifies, Hiyoshi undergoes significant maturation. A pivotal moment in his development occurs when he voluntarily dismantles his beloved creation, Tako-chan, to obtain critical spare parts for a necessary repair, a selfless act that showcases his growing dedication to the team and its mission above his own attachments. The death of his mother, Mitsuyo Gō, during a Boazanian attack further deepens his resolve, strengthening his commitment to protecting Earth and continuing the search for his missing father.

His key relationships are central to his character arc. The dynamic with his eldest brother Kenichi is particularly important; while the two brothers argue from time to time, Kenichi is often seen encouraging Hiyoshi and taking on a father figure role, guiding him through challenges. With Megumi Oka, the sole female member of the team, Hiyoshi shares a warm bond, eventually coming to view her as an older sister, even affectionately calling her nee-san at times. As the series progresses, Hiyoshi’s technical innovations, which include refinements to the systems of Voltes V, gradually earn him greater respect and trust from his fellow teammates, helping him overcome any initial perceptions of being merely the child of the group. The quest to find his father and the revelation of his family's unique heritage as half-Boazanians remain driving forces for Hiyoshi throughout the team’s struggle against the Boazanian empire.