Location: Japan
Scariest fact: They may recruit people via their own website and magazine
Murder weapons: Bombs and guns. 

The Yamaguchi-gumi are one of many Yakuza gangs in Japan. The Yakuza are generally highly organized—they even have corporate logos, business, cards and an office—and have a legacy of being super strict. (To atone for mistakes and to leave the gang, members have their fingers cut off.) The numbers for Yamaguchi-gumi range anywhere between 25,000 and 40,000, and the Obama Administration has acted in an effort to curb their influence and activity. It may have worked. They have become less violent, and the Yamaguchi-gumi will lead you to believe that they’re now a social awareness organization with a website and theme song. Some critics believe the website is a recruitment tactic. It’s hard to turn a blind eye to a history of extortion, intimidation, fraud, political corruption, and assassinations. Old habits die hard.