Mizuho Bank's loans to yakuza and other shady individuals through its group credit company Orient Corp. may be just the tip of the iceberg as corporate Japan struggles to break off its long-held ties with organized crime.

On Monday, Mizuho released the results of a third-party investigation report in which the mega-bank blamed "lax awareness" for its failure to take action on 228 mob-linked loans for cars and electronics totaling ¥200 million.

As part of a business improvement plan submitted to the Financial Services Agency, Mizuho also announced the punishment of 54 executives and vowed to take preventive steps to avoid lending to "anti-social elements," which include not only gangsters but also "sokaiya" racketeers and convicted fraudsters.