Yokoyama Sakujirō , was one of the earliest disciples of Kanō Jigorō. He was part of the Kōdōkan Shitennō or Four Guardians of the Kodokan along with Yoshitsugu Yamashita, Tsunejirō Tomita, and Shirō Saigō.

Kanō Jigorō was a Japanese educator, athlete, and the founder of judo. Along with ju-jutsu, judo was one of the first Japanese martial arts to gain widespread international recognition, and the first to become an official Olympic sport. Pedagogical innovations attributed to Kanō include the use of black and white belts, and the introduction of dan ranking to show the relative ranking among members of a martial art style. Well-known mottoes attributed to Kanō include "maximum efficiency minimal effort" and "mutual welfare and benefit" .