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. The kumicho of the gang, Kenichi Shinoda, decided to make inroads into the capital of Tokyo, which was traditionally not Yamaguchi-gumi turf.

Community content is available under CC-BY-SA unless otherwise noted.