Mikinosuke Shiraki is an elderly man with gray hair, black eyes, and a formal appearance marked by a suit, glasses, a beard, and a mustache. He is the head of the Shiraki Group, a powerful conglomerate with influence in both business and politics both in Japan and internationally. In his youth, he was active as an amateur boxer, which gave him a deep, practical understanding of the discipline and its role in character education. He serves as the honorary chairman of the Japan Boxing Gym and is the grandfather of Yoko Shiraki, whom he deeply loves and supports. His vast wealth and connections allow him to act as a major benefactor in the boxing world. He is the one who established the Shiraki Boxing Club after recognizing the immense boxing potential in Toru Rikiishi, and he funds Rikiishi’s professional career. Earlier in the story, he also provides the financial backing for the boxing tournament held in the juvenile detention center where Joe Yabuki and Rikiishi first meet. Mikinosuke's role is that of a powerful, behind-the-scenes figure who enables the professional opportunities of key boxers through his resources and his network. He is a figure who understands the value of boxing not only as a sport but as a means of personal development, and his motivations are driven by a combination of business acumen, past experience in the ring, and a strong affection for his granddaughter. Throughout the series, his presence remains that of a respected elder and financier; his granddaughter Yoko later takes over his gym’s leadership. His notable abilities are not physical combat but rather his organizational and financial power, as well as his seasoned insight into the world of boxing.