The Yakuza go back quite far in Japanese history, with references to them occurring as early as the 17th century.
If you spend any time in a large Japanese city you'll eventually see and hear the speaker trucks blaring old military airs. The trucks are usually pAinted black, and are marked with the chrysanthemum seal and/or old battle flags. These nuts generally drive around in noisy convoys, stopping in front of the occasion train station, government office building, or immigration office were jack-booted thugs in smart uniforms with swastikas on their shoulders will rant against good and normalcy.
The Yakuza usually spend most of their time breaking legs, pimping prostitutes, or skimming the profits of their more "legitimate" enterprises. Being right-wing nuts is a part-time occupation for them.