
The Yamaguchi-gumi is Japan's largest yakuza organization, founded in 1915 by Harukichi Yamaguchi as a Kobe dockworkers union. The union would later become one of the largest criminal organizations in the world, having more than 55,000 members and 850 clans. The gang operated from Kobe, but it had international operations across Asia as well as in the United States; it was involved in extortion, gambling, prostitution, arms/drug trafficking (the latter to a lesser extent, and mostly exporting drugs), real estate/construction kickback schemes, stock market manipulation, and internet pornography.
Kazuo Taoka, boss of the gang from 1946 to 1981, expanded into Osaka and Yokohama during the 1960s, resulting in his absorption of the rival Honda-kai, his takeover of the Korean Meiyu-kai's turf in Osaka, the conquest of the Miyamoto-gumi, and a war with the Inagawa-kai for control of Tokyo which was ended by the intervention of Yoshio Kodama. In 1972, the Yamaguchi-gumi allied with the Inagawa-kai, but an assassination attempt on Taoka in 1978 resulted in an all-out gang war with the Matsuda-gumi. The generation gap between the older and younger gang members led to rivalries forming within the gang; as many as 23 bosses of affiliated gangs were expelled or disciplined for opposing syndicate policy, and the Yamaguchi-gumi had grown too big and too dependent on Taoka's leadership. In 1980, 200 Yamaguchi-gumi members were sent to Sapporo, Hokkaido to open a branch office there, but they were met by 800 members of local underworld gangs, and 2,000 riot police kept the two groups apart. However, the gangsters were forced to return home a day later empty-handed, having been quarantined at a ski resort and prevented from opening an office. In 1981, Taoka died of a heart attack, and the police cracked down on his syndicate. The ensuing succession crisis resulted in the Yama-Ichi War, which resulted in a Yamaguchi-gumi victory and the destruction of the secessionist Ichiwa-kai. By 2000, the Yamaguchi-gumi boastd 34,000 men, nearly half of all yakuza identified by the police. During the 21st century, the kumicho of the gang Kenichi Shinoda decided to make inroads into the capital of Tokyo, which was traditionally not Yamaguchi-gumi turf.