As one of Japans biggest corporate dramas in years, the furore surrounding optical equipment maker Olympus already boasts a rich cast of characters including a disgraced chairman, the British president he fired and a hapless successor struggling to clean up the mess.
But some observers wonder whether shadier players - Japans notorious yakuza crime syndicates - may also have a role in the scandal.
The Olympus case appears to bear all the hallmarks of the sort of financial frauds in which organised crime groups have been involved in the past, says Velisarios Kattoulas of Poseidon Research, which advises multinationals on doing business in Japan and other Asian nations.
Mr Kattoulas says people his firm has spoken to on the fringes of organised crime are concerned whether one of Japans most powerful yakuza groups was involved.
Facta - the Japanese magazine that uncovered the more than $1bn in suspect payments connected with the acquisitions - in October highlighted possible involvement in the scandal of a company suspected of having a relationship with antisocial forces, a euphemism used in Japan for the yakuza.
Olympuss new president, Shuichi Takayama, has waved aside such suggestions, although he has been forced to reverse earlier denials and admit that former chairman Tsuyoshi Kikukawa and other executives used a string of corporate acquisitions to cover up hidden losses dating from the 1990s.
Asked by journalists on October 26th about the possibility of involvement by antisocial forces in the scandal, Mr Takayama said, I absolutely do not recognise this.
In an article on the scandal this month, the online magazine Gendai Business argued that speculation that yakuza had a central role was premature. Even if there are strange transactions, it does not look as if strange forces were directly involved, the magazine said.
No evidence of yakuza involvement has so far come to light, but the very possibility was enough to give Michael Woodford, the British Olympus president who was fired after asking questions about the transactions, cold and clammy hands.
Nor are such fears ridiculous. Nobody doubts that the yakuza, which claim roots in traditional associations of gamblers and peddlers, remain a force in Japanese society. Police have designated 22 syndicates as boryokudan - violent groups - with nearly 80,000 members and associates.
Police also say the yakuza have been stepping up efforts to expand beyond sectors such as gambling, prostitution, drug dealing and protection rackets into legitimate businesses including finance and securities trading.
[Yakuza groups] are increasingly active in acquiring funds from ordinary society, the National Police Agency said in a report released this year.
The police say syndicates often work through legitimate business, with counterparties sometimes unaware they are dealing with the mob. Companies trying to cover up scandal or conceal losses are particularly vulnerable.
The push into finance and legitimate business has ironically been encouraged by authorities increasing efforts to limit the operations of the yakuza, which have for decades operated far more openly than crime groups in other advanced nations.
Legislation in the early 1990s put tight restrictions on the activities of designated syndicates and their members, and police have in the last couple of years launched a series of campaigns targeted at some of the most violent groups.
Authorities this year also seized on a gambling scandal involving sumo wrestlers and yakuza-linked bookies as a chance to force a very public clean-up of the traditional sport, long a gangster favourite.
More threateningly for underworld incomes, prefectures around Japan have introduced regulations aimed at cutting ties between the yakuza and legitimate businesses.
Penalties are light: the Tokyo ordinance, which took effect last month, merely threatens to admonish companies found involved in non-illegal transactions with yakuza members or groups. But the regulations and promises of policy support do appear to have encouraged many businesses to cut ties with mob groups.
The risk is that such efforts will merely push organised crime deeper underground and into new enterprises. More fundamental progress will need public confidence that the power of the yakuza is really being curbed.
That could depend in part on whether investigations into Olympus can get to the bottom of the scandal, exposing any organised crime involvement should it exist. But probes into past scandals have sometimes failed to allay concerns about possible yakuza involvement.
In 2006, an investigation into deals involving Livedoor, a Japanese internet group, were undermined by the death of Hideaki Noguchi, a former group executive and key witness. Police ruled that Noguchi committed suicide, but Japanese news magazines have suggested others might have inflicted the multiple knife wounds that killed him.
Mr Kattoulas says some on the fringes of the crime world hint there could be more such tragedies to come.
One of the people we spoke to said he would be not at all surprised if this [Olympus] investigation goes cold because of mysterious deaths and unexplained suicides, Mr Kattoulas says.
The Financial Times Limited 2011