The Black Dragon Society (Kokuryūkai) was a historical paramilitary organization of Japan, active from 1901 to 1946.
An ultra-nationalistic group, the organizations original goal was to support efforts to drive the Russian Empire away from East Asia and promote Japanese expansion in the area. Members included several politicians, military officers and professional secret agents.
The Society established an espionage network active in Japan, Russia, Manchuria, Korea and China. They were in alliance with the official Japanese Military in campaigns lasting from the 1900s to the 1920s. Their activities included espionage, sabotage, assassination and spreading of misinformation. They also supported certain guerilla groups in China, having some influence over the Chinese Civil War.
During the 1930s and 1940s, the society had a more public influence in Japanese politics while its espionage network expanded throughout Asia, Europe, North Africa, South America and North America. The yellow press, particularly in the United States, seized the opportunity to portray them as a fifth column active within the nation. While there were actual members active in Caliifornia c. 1942, their numbers and actual level of activity remains uncertain.
The Society featured in many "lurid" novels and short stories, published in and out of the pulp magazines. In the 1940s, they had several fictional appearances in American films and Republic Films' film serials. While the historical society disbanded early in the Allied Occupation of Japan (1945-1952), their role in fiction has hardly diminished.