Born in Gifu Prefecture, Kōyama's life took an unconventional turn when he abandoned his studies at Nihon University to pursue a career in the film industry. He joined the prestigious independent production company Kindai Eiga Kyokai, where he had the privilege of working as an assistant director under the tutelage of renowned directors such as Kaneto Shindō, Kōzaburō Yoshimura, and Tadashi Imai.
This hands-on experience proved to be a valuable stepping stone for Kōyama, as he eventually made his directorial debut in 1971 with the children's film Koi no iru mura. His subsequent film, Futatsu no hāmonika, released in 1976, garnered him a New Directors Citation from the esteemed Directors Guild of Japan.
Kōyama's reputation continued to grow, and his 1983 film Hometown was selected to be showcased at the 13th Moscow International Film Festival. His 1987 film, Hachiko Monogatari, which tells the heartwarming story of the loyal dog Hachikō, went on to become the top-grossing Japanese film of that year.
Throughout his illustrious career, Kōyama has been recognized for his distinctive humanistic perspective, which has endeared him to audiences and critics alike.
