The whistle-blowing erupted a few days before May 17, the day Resona, the nation's fifth-largest banking group, announced its capital had tumbled below regulation levels.

During the week leading up to May 17 -- when the government promised it would inject 2 trillion yen into Resona Holdings, Inc. -- some reporters and politicians received tapes and documents apparently showing that Financial Services Agency officials pressured Resona's auditors into fudging the books and pretending no capital shortfall existed.

The confusion has unleashed a furor of doubt: What else are regulators trying to hide? Could Resona Bank, the banking group's core entity, actually be insolvent? What about the other major banks?