Sanada clan
Nakayama was born on April 13, 1913, in the Yamaguchi prefecture of Japan. He was descended from the Sanada clan, who were known as kenjutsu instructors, from the Nagano region. Nakayama's grandfather was Naomichi Nakayama, a surgeon in Tokyo, who had also been the last of the family to teach kenjutsu. Nakayama's father was Naomichi Nakayama, an army physician and a "judoka" (practitioner of judo). His father was assigned to Taipei, so Nakayama spent some of his formative years there. Apart from his academic studies, he participated in kendo, skiing, swimming, tennis, and track running.