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
Judo and Dong-Sik Yoon. Kano Jigoro's Kodokan judo is the most popular and well-known style of judo, but is not the only one. The terms judo and jujutsu were quite interchangeable in the early years, so some of these forms of judo are still known as jujutsu or jiu-jitsu either for that reason, or simply to differentiate them from mainstream judo. From Kano's original style of judo, several related forms have evolved—some now widely considered to be distinct arts: Kano's vision for judo was one of a martial way that could be practiced realistically. Randori (free practice) was a central part