yakuza
Yakuza literally translates to "Bad, crooked." Lives up to its name. Unlike other underworld mass criminal organization, Yakuza has heavy influence in Japanese politics. One example is during the WW2, when Yakuza members flourished throughout asia, stealing, making brothels, prostitution, drug sales. They were unstoppable.

Even today, they have close ties with politicians, and control most of the entertainment industry and other areas.

Quite a bit of percentage of the Yakuza members prove to be of Korean ethnicity. An explanation would be that Koreans living in Japan aren't recognized as "Japanese" meaning that they are still subjected as aliens. Therefore, socially they become an outcast. It is natural for them to join social-outcast groups such as the Yakuza.
Yakuza unlike other organized criminals have had relatively powerful influence in politics in Japan, especially during WW2 when Japan wrongfully committed crimes throughout Asian nations and Dutch.