Unlike more traditional yakuza, uyoku did not maintain territories—they leveraged their violence for political gain. The most famous group before World War II was the Kokuryū-kai (??), or Black Dragon Society. The Kokuryu-kai was a secret ultra-nationalist umbrella organization whose membership was composed of government officials and military officers as well as many martial artists and members of the Japanese underworld who engaged in political terrorism and assassination. They also provided espionage services for the Japanese colonial government. Kokuryū-kai engaged in contraband operations including the Chinese opium trade, as well as prostitution and gambling overseas which provided them with funds as well as information
During the post-War rationing, the yakuza controlled the black market much in line with traditional tekiya operations. At the same time, they also moved into controlling major sea ports as well as the entertainment industry. The biggest yakuza umbrella group, the Yamaguchi-gumi, emerged in the Kansai region, which had a large entertainment industry in the city of Osaka as well as a major sea port in Kobe. American occupation forces fought against them in vain and conceded defeat in 1950. Yakuza also adapted to a more western style, including wearing clothing reminiscent of US gangsters, and began to use firearms. At this point, tekiya and bakuto no longer confined themselves to their traditional activities and expanded into any venture they found profitable. At the same time gurentai began to adopt traditional roles of tekiya and bakuto. They also began to feud among themselves, jockeying for power and prestige.
In the 1960s, Yoshio Kodama, an ex-nationalist, began to negotiate treaties with various groups, first with the Yamaguchi-gumi of Kazuo Taoka and Tōsei-kai of Hisayuki Machii and eventually with the Inagawa-kai. Fights between individual gangs, however, are ongoing.