— When Olympus fired Michael Woodford, its British chief executive, in October, the company said he had been unable to conform to Japanese-style management.

Since then, Mr. Woodford has taken the decidedly non-Japanese step of publicly rebuking his employer and, by blowing the whistle on his own company, has done something rare for a chief executive anywhere in the world. His allegations of billion-dollar malfeasance have set off investigations on three continents. Olympus has since acknowledged long-running efforts that it says were meant to hide steep financial losses. Now, Mr. Woodford is making his next unorthodox move.

On Friday he plans to return to Olympus headquarters for a board meeting, where he said he would demand that the entire board come clean on details of their actions and step down to take responsibility. (Because of a technicality, Mr. Woodford is still an Olympus director.)

He said he would offer to return to Olympus as president and lead a turnaround at the iconic Japanese company that some analysts and investors fear risks being delisted from the Tokyo Stock Exchange and could even be on the verge of collapse.

“I want to look them in the eye and talk to them directly,” Mr. Woodford said at an interview over dinner Wednesday in Tokyo, shortly after flying from London and being thronged by Japanese reporters eager to speak with the outsider who dared to speak up.

“I hope the company won’t be delisted, but I certainly wouldn’t compromise getting to the truth, because staying listed shouldn’t be the criteria,” he said.

Olympus’s taking Mr. Woodford up on his comeback offer might be a long shot. But hundreds of rank-and-file employees at Olympus have signed petitions urging the company’s top management to resign and calling for Mr. Woodford to return — a rare uprising in a nation that values company loyalty above all.

If he were reinstated, Mr. Woodford said, change at the company would be swift. And any housecleaning would include unwinding Olympus, a maker of medical imaging products and digital cameras, from the jumble of unrelated small businesses it acquired as part of the financial cover-up.

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“The sooner you get out of the cat food and face cream and microwavable plates, the better,” he said. “Almost all of it, I would shut quickly.”

By challenging the Olympus board, Mr. Woodford — the first non-Japanese to lead Olympus in its 94-year history and one of few foreign chief executives in the country — will be confronting a closed, homogenous corporate culture that changed little through Japan’s freewheeling bubble economy of the late 1980s, the subsequent bubble-bursting in the ’90s and the national economic stagnation ever since.

Truly independent board members are rare in corporate Japan, and foreign ones are even rarer. Cozy cross-shareholding arrangements typically ensure compliant stockholders who tolerate mediocre management, or look the other way in cases of boardroom impropriety. And in a mixture of fact and myth, often lurking in the background of the Japanese business world are tales of corruption and rumored links to the country’s infamous organized crime syndicates, the yakuza.

In the case of Olympus, investigations by public officials in Japan and law enforcement agencies in the United States and Britain have focused on $687 million in advisory fees paid in 2008 to an obscure financial adviser for Olympus’s acquisition of the British medical equipment maker Gyrus — fees equal to roughly a third of the $2 billion acquisition price and more than 30 times the going rate. Olympus also acquired three small Japanese companies from 2006 to 2008 with little in common with its core business for a total of $773 million, only to write down most of the value of each within the same fiscal year it was acquired. Olympus has said those acquisitions were part of a plan to hide past losses on investments, and blamed three executives — including the former president Tsuyoshi Kikukawa, who has since been dismissed. Mr. Kikukawa also remains a board member, though it is unclear whether he will be present at Friday’s board meeting. The company has appointed a committee of outside legal experts to investigate the cover-up. Olympus has declined to comment on the investigations or to make its executives or former executives available for interviews.

Criminal investigators in Japan are also trying to determine whether at least $2 billion more in unaccounted funds went to companies with links to organized crime, according to an investigator’s memo. Olympus strongly denied those allegations earlier this week.

It has been a roller-coaster ride at Olympus for Mr. Woodford. He rose from a surgical salesman at Olympus to, at the age of 29, managing director of the company’s British medical subsidiary, and then eventually ran Olympus’s entire business in Europe.

But Mr. Woodford said he ran into what appeared to be strange goings-on at the company. He flew to Tokyo to tender his resignation in 2008, he said, when he found out about the Gyrus acquisition, for example. Although the acquisition should have fallen under Mr. Woodford’s purview, the deal to buy the British medical equipment maker was arranged from Tokyo by the president at the time, Mr. Kikukawa.

Before Mr. Woodford could submit his resignation, Mr. Kikukawa assigned him to oversee all of Olympus’s businesses in Europe and offered to make him a board member — a startling promotion. Mr. Woodford, who said he suspected no criminal activity, decided to stay.

In February, Mr. Kikukawa again promoted Mr. Woodford, this time to company president, in recognition of the substantial growth in the

company’s European operations. Anointing a British executive was seen as a bold move for the company. But Mr. Kikukawa kept his chief executive title.

Their relationship quickly deteriorated, Mr. Woodford said. When the Japanese finance magazine Facta published an article in July questioning a series of Olympus acquisitions, Mr. Woodford says he discussed it with Mr. Kikukawa, who he said told him not to worry about it. But when Mr. Woodford continued to press the matter in what he called “exceptionally heated and emotional” meetings and letters, Mr. Kikukawa agreed to give up his chief executive title to Mr. Woodford.

That move, effective Oct. 1, in theory gave Mr. Woodford the right to nominate top management. But at a meeting on Oct. 14, the board unceremoniously dismissed Mr. Woodford, telling him to leave the country. “I was very shaken,” he said.

Whatever happens with Mr. Woodford’s effort to return to Olympus, analysts say it is uncertain how deeply public investigators in Japan will dig into the cover-up, including allegations of organized crime links. Japanese police have recently bolstered efforts to crack down on the yakuza and sever its long-standing ties to industry and politics.

But financial regulators have seldom been keen to shed light on potential criminal entanglements that might roil Japanese markets and scare away foreign investors, said Tadashi Kageyama, senior managing director and head of Asia and Japan for Kroll, a global risk consultancy with expertise in fraud and corporate governance. That ambivalent stance, he said, has led to inconsistent regulatory actions that are prone to political pressure and have hurt long-term market confidence.

On Thursday, Mr. Woodward will meet with Japanese authorities to submit evidence.

“Now the greater good that motivates me is what’s good for Japan,” he said. “It’s gone way beyond Olympus now.”