Professor Gennosuke Yumi serves as director of the Photon Power Laboratory, having taken the helm after its founder, Juzo Kabuto. A seasoned scientist and mentor, he guides pilots of Mazinger Z and Great Mazinger in their battles against adversaries like Dr. Hell and the Mykene Empire. As father to Sayaka Yumi, pilot of the Aphrodite A, he oversees laboratory operations while strategizing countermeasures against mechanical beasts. Trained under Juzo Kabuto’s tutelage, his mastery of robotics and photon energy technology enabled him to forge the Aphrodite A from Juzo’s blueprints. During combat, he dissects enemy vulnerabilities, his steadfast composure counterbalancing the pilots’ fiery resolve. Though prioritizing civilian and personnel safety during assaults on the lab—activating shields or ordering evacuations when overwhelmed by threats like Ashura Mazinger—he ultimately trusts the pilots’ instincts when crises demand decisive action. In global emergencies, he partners with government agencies to neutralize planetary dangers and mobilizes technical expertise to stabilize crises. His mentorship of Koji Kabuto walks a tightrope between curbing recklessness and respecting Juzo’s legacy of boldness. He similarly guides Tetsuya Tsurugi’s maneuvers with tactical insights during Great Mazinger missions. Having cut his teeth aiding Juzo’s foundational experiments, he ascended to lead the Photon Power Lab, appearing across Mazinger iterations like *Mazinger Z vs. Devilman*, *Mazinger Z vs. The Great General of Darkness*, and *Mazinkaiser* OVAs. Anchoring chaos with methodical precision, he maintains strategic oversight whether upgrading robotic systems or analyzing enemy tech. Fatherly concern for Sayaka’s safety subtly steers his crisis responses, yet his focus remains unwavering: to safeguard humanity through innovation, not personal ambition.