TOKYO (Reuters) - Ousted Nissan boss Carlos Ghosn walked out of a Tokyo prison on a $9 million bail on Wednesday, slipping past reporters in a face mask and moving closer to mounting a defense against financial misconduct charges that he has called “meritless”.

Ghosn, among the world’s most prominent auto executives whose dramatic rescue of Nissan two decades ago made him a celebrity in the industry and in Japan, was barely recognizable as he left Tokyo Detention House where he had been detained for more than 100 days in a small cell with no heating.

Surrounded by security guards and dressed in a workman’s uniform and a blue cap, Ghosn’s face was obscured by thick glasses and the surgical-type mask, a far cry from his usual tailored suits. He managed to avoid many of the reporters camped at the site before being whisked away in a small Suzuki van.

Ghosn paid the 1 billion yen ($9 million) bail, among the highest ever in Japan, after the Tokyo District Court rejected a last-ditch appeal by prosecutors to keep him in jail.

Ghosn, also the former chairman of Renault and Mitsubishi Motors, has agreed to strict bail conditions and given assurances he will remain in Tokyo, surrender his passport to his lawyer and submit to extensive surveillance.

He has agreed to set up cameras at the entrances and exits to his residence, and is prohibited from using the internet or sending and receiving text messages. Ghosn is also banned from communicating with parties involved in his case, and permitted computer access only at his lawyer’s office.

He faces charges of aggravated breach of trust and under-reporting his salary by about $82 million at Nissan for nearly a decade. If convicted on all charges, he faces a maximum jail sentence of 15 years, prosecutors have said.

“I am innocent and totally committed to vigorously defending myself in a fair trial against these meritless and unsubstantiated accusations,” he said in a statement on Tuesday.

The finance minister of France welcomed Ghosn’s release, saying the executive would now be able to defend himself “with greater ease”. Ghosn holds a French citizenship.

Slideshow ( 16 images )

BUILDING DEFENSE

The release will allow Ghosn - the architect of Nissan’s automaking partnership with Renault and Mitsubishi - to meet his new legal team more frequently and build a defense ahead of trial, which could be several months away.

Slideshow ( 16 images )

Last month, Ghosn hired lawyer Junichiro Hironaka, nicknamed “the Razor” for his success at winning acquittals in several high-profile cases, to replace Motonari Otsuru who once ran the prosecutor’s office investigating him.

Hironaka’s appointment suggests a shift to a more aggressive defense strategy. He has already said that the charges against Ghosn should have been dealt as an internal company matter and that Japan was out of step with international norms by keeping his client in jail.

The case has cast a harsh light on Japan’s criminal justice system, which allows suspects to be detained for long periods and prohibits defense lawyers from being present during interrogations that can last eight hours a day.

While the bail is a significant step, Ghosn still faces a criminal justice system with a conviction rate of 99.9 percent.

Credited with reviving Nissan in the early 2000s, Ghosn was one of the auto industry’s most powerful figures as head of the Nissan-Renault-Mitsubishi alliance, whose combined sales rank it as one of the world’s biggest automakers.

At the time of his arrest, he had been seeking a full merger of the companies, an idea opposed by many Nissan executives.

However, his arrest has since muddied the outlook for the alliance, which is based on a web of cross-shareholding and operational integration.