Kan? Jigor? (?? ???, 28 October 1860 – 4 May 1938[1]) was a Japanese educator and athlete, the founder of Judo. Judo was the first Japanese martial art to gain widespread international recognition, and the first to become an official Olympic sport. Pedagogical innovations attributed to Kan? 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 Kan? include "maximum efficiency with minimum effort" (???? seiryoku zen'y?) and "mutual welfare and benefit" (???? jita ky?ei).