Mikinosuke Shiraki is a supporting character in the anime and manga Tomorrow's Joe. He is the elderly, wealthy head of the Shiraki Group, a prominent business and political family, and holds the title of honorary chairman of the Japan Boxing Gym. In his youth, Shiraki was an active amateur boxer, which gave him a deep, philosophical understanding of the educational and character-building value of the sport. He is also the grandfather of Yoko Shiraki, whom he deeply loves and trusts. His motivations are rooted in a desire to nurture promising boxing talent and to elevate the sport. He first becomes involved in the story by funding a boxing tournament inside the juvenile detention center where the protagonist Joe Yabuki and his rival Toru Rikiishi meet. Recognizing Rikiishi's exceptional potential, Shiraki opens the Shiraki Boxing Club specifically to sponsor Rikiishi's professional career, providing financial stability and top-tier training conditions. Throughout the series, he acts as a pillar of the boxing establishment, offering resources and influence from behind the scenes. His relationship with Yoko is one of mutual affection and respect; he eventually entrusts her with managing the gym, allowing her to play a more active role in the world of boxing. Shiraki himself does not undergo a major character transformation; rather, he remains a steady, benevolent authority figure whose past experience in the ring informs his support for the younger generation. His notable abilities lie not in physical combat but in his wealth, connections, and seasoned judgment of boxing talent and character.