Professor Gennosuke Yumi directs the Photon Power Laboratory, succeeding his mentor Juzo Kabuto. A middle-aged scientist with dark hair, a mustache, and glasses, he typically wears a white lab coat over a yellow shirt and black tie. As Sayaka Yumi's father, he shares a professional yet caring dynamic with her, though not overtly demonstrative. His background includes close collaboration with Juzo Kabuto, granting him deep knowledge of Super Alloy Z and Photon Energy research. This expertise enabled him to build the Aphrodite A robot from Juzo's notes, later entrusted to his daughter for combat. He demonstrates strategic acumen, frequently identifying enemy Mechanical Beast weaknesses and advising pilots like Koji Kabuto. Despite Koji's occasional recklessness, he responds with patience, prioritizing pilot safety and the laboratory's mission over reprimands. During assaults by Dr. Hell and Baron Ashura, he coordinates the laboratory's defense, activating barrier systems and overseeing evacuations when threats like Ghost Mechanical Beasts endanger the facility. He participates in high-level government meetings addressing the Dr. Hell crisis, advocating for Mazinger robots as countermeasures. His leadership involves managing staff and resources, such as deploying the Kaiser Pilder to aid Koji against android assassins. In the *Mazinkaiser* OVA continuity, he faces intensified threats, including an assassination attempt by Ashura disguised as staff during his birthday; he survives due to his team's bomb-disarming efforts. Later, when the Venus A transforms into a Ghost Mechanical Beast, he orchestrates the laboratory's evacuation while supporting Koji's deployment of the Mazinkaiser against Hell Castle. Across adaptations, his role and demeanor remain consistent, though his given name appears as "Yanosuke" in *Shin Mazinger Shougeki! Z Hen*. His scientific contributions and crisis leadership highlight his commitment to using Photon Energy technology for humanity's protection, often invoking a "sink with the ship" mentality when facing imminent defeat.