Tokyo ( CNN ) -- As Japanese authorities widen their investigation into ties between financial institutions and organized crime , an investigative reporter says the current allegations have left with a sense of `` déjà vu . '' `` In 2004 , Citibank ( Japan ) lost their private banking license because they were allowing yakuza to do many complex transactions , '' Jake Adelstein , author of `` Tokyo Vice '' and an expert on Japan 's mafia -- known as the yakuza -- told CNN . `` They got spanked in 2009 for failing to update their databases and allowing yakuza to do business with them again . The Financial Services Agency ( FSA ) , the country 's financial regulator , will send inspectors to Japan 's three largest banks -- Mizuho Bank , Tokyo Mitsubishi UFJ Bank and Sumitomo Mitsui Bank -- to `` review over their corporate governance , legal compliance and overall risk management , '' said Hiroki Kato , director of the Inspection Bureau of the FSA . The on-site inspections are scheduled to begin next week . All three banks declined to comment on the review when contacted by CNN . Ties to gangs . Mizuho has already come under scrutiny after 54 executives , including the bank 's president , were punished after it was revealed an affiliate made more than $ 2 million in loans to people with ties to organized crime . Yakuza is the name given to Japan 's organized crime syndicates . Adelstein -- the only American who has worked a crime beat for the Yomiuri Shimbun , Japan 's largest newspaper -- has called them `` Goldman Sachs with guns '' because of the financial prowess and sometimes brutal means . `` The yakuza have been tremendously successful because they can work out in the open , '' Adelstein told CNN . `` They have business cards , they have office buildings . People know who they are -- they have fan magazines and they have a lot of money . '' Strict code . Members are said to follow a strict code of discipline -- and often sport full body tattoos . The biggest and wealthiest yakuza gang -- the Yamaguchi-gumi -- is said to number nearly 40,000 members . Robert Feldman of Morgan Stanley Japan once called the Yamaguichi-gumi `` Japan 's largest private equity group . '' Belonging to a yakuza gang itself is not a crime . But members are known to engage in drugs , prostitution and gambling . After recent crackdowns by Japanese authorities , yakuza are making more strides into white-collar crime , experts say . `` So if you have a lot of money and a lot of information and you can use blackmail and extortion to do insider trading it can make quite a tremendous financial force , '' Adelstein said . `` Yakuza have tremendous political connections and they have a lot of information to blackmail people . ''
Three of Japan 's largest banks are under scrutiny for making loans to underworld groups . Mizuho has punished 54 executives loans to people affiliated with the yakuza , the Japanese mafia . Expert : `` Yakuza have been tremendously successful because they can work out in the open ''