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 in the United States the naval academy. Judo suddenly had its first strong roots in the United States. Yoshiaki decided to return to Japan, but other Japanese Judo participants followed his example. The judo concentration was mainly centered in Washington before World War II, but several centers existed on the west coast, including Tokugoro Ito's dojo in Los Angeles, which was founded in 1910. Judo first entered the Western United States when Dr. T Ito began teaching Judo in Denver in the 1930s. During World War II Judo was banned in many areas due to the Japanese fear; however, a boom followed the war.