All-Japan Judo Championships
However, Kaminaga was completely outclassed when he participated in the Meiji University judo team's sparring sessions. This convinced him to enter Meiji University, and he continued to practice judo at the Kodokan Institute. Kaminaga had several career choices after graduating, but became an employee of Fuji Steel (currently Nippon Steel) at the recommendation of Meiji University alumnus and 1958 World Judo Championships gold medalist Koji Sone. He finished in second place behind Sone in the 1958 World Championships, and won a then-unprecedented three championships at the All-Japan Judo Championships from 1960–1961 and 1964 to become the top heavyweight judo competitor in Japan along with Isao Inokuma. Inokuma would remain Kaminaga's rival and close friend throughout his life.