Rank in Judo are ranked in ascending numerical order. The ninth ("kudan") and tenth degree black belt ("jūdan") and, theoretically, those higher, have no formal requirements. Only 15 individuals have been promoted to the rank of Kōdōkan 10th dan. On January 6, 2006, three individuals were promoted to this rank simultaneously: Daigo Toshirō, Ichirō Abe, and Ōsawa Yoshimi. This is the most ever at the same time, and the first in 22 years. No one has ever been promoted to a rank higher than 10th "dan", but in theory the Judo rank system is not limited to 10 degrees of black belt. The
Rank in Judo are yet to attain that level and who hold grades. Those who hold "dan" grades are collectively termed (literally "person who has dan") and those with "kyū" grades are , literally "person without dan". This ranking system was introduced by Kanō Jigorō, the founder of judo, in 1883. However, the current system is not the original one, but based on Kanō's last system introduced between 1926-1931, with some modification shortly after Kanō's death in 1938. The first "dan" grades were awarded to his students Saigō Shirō and Tomita Tsunejirō. Since then it has been widely adopted by modern martial arts.