TOKYO (AFP) – Nissan and Mitsubishi shares plunged Tuesday, as the automakers prepared to oust chairman Carlos Ghosn a day after he was arrested for alleged financial misconduct.

Ghosn’s arrest sent shockwaves through the auto industry, where he was a towering figure, as well as Tokyo markets, which opened lower as Nissan fell more than six percent.

And his legacy appeared in danger of total collapse, with his own handpicked successor as Nissan CEO accusing Ghosn of accruing too much power, in what he called the ‘’dark side’’ of his leadership.

The spectacular fall of the Brazil-born executive also raised questions about the future of the sometimes fractious alliance he led of Nissan, Mitsubishi and Renault.

Both Nissan and Mitsubishi have said they will propose his removal as chairman, with Renault’s board also meeting to discuss his fate.

On Tuesday there were still many unanswered questions about the allegations against a man long credited with an almost magical ability to turn around ailing auto companies.

Nissan’s CEO said a months-long investigation prompted by a whistleblower had uncovered years of financial wrongdoing, including under-reporting of Ghosn’s salary and misuse of company assets.

Prosecutors said they were holding him as they investigated allegations he had under-reported his income by around five billion yen ($44.5 million) over five years.

The shock of his arrest was compounded by the harsh language levelled against him by Nissan CEO, Hiroto Saikawa, who in a press conference accused Ghosn of accruing too much power.

‘’Too much authority was given to one person in terms of governance,’’ he told reporters at Nissan’s headquarters in Yokohama on Monday.

‘’I have to say that this is a dark side of the Ghosn era which lasted for a long time.’’

Saikawa said he was still thinking through whether Ghosn was ‘’a charismatic figure or a tyrant.’’

It was an almost unthinkable turn of events for Ghosn, 64, who had earned a virtually unparallelled reputation, particularly in Japan, for his role in resurrecting Nissan.

Ghosn has dominated the country’s corporate landscape, and is a well-known figure among the general public, who know him as ‘’Mr Fix It’’, partly through a popular manga comic of his life story.

But the tables had turned Tuesday, with the Yomiuri Shimbun described executives at Nissan slamming Ghosn as ‘’greedy.’’

‘’He says the right things, but in the end it’s all about money,’’ the daily quoted employees as saying.

It was unclear how long Ghosn could be held, or even when prosecutors would officially announce the charges against him.

Nissan said it had uncovered years of financial misconduct by Ghosn and Representative Director Greg Kelly, including under-reporting of income and inappropriate personal use of company assets.

Saikawa gave few details and refused to confirm reports that Ghosn under-reported his income by 5 billion yen, or around $44 million, over five years from 2011.

He said an ongoing investigation limited what details could be shared, and refused to be drawn on whether other people were involved, saying only: ‘’These two gentlemen are the masterminds, that is definite.’’

Saikawa insisted the partnership among Nissan, Renault and Mitsubishi ‘’will not be affected by this event,’’ but had no details on how the other firms would respond, or who might succeed Ghosn.