Carlos Ghosn, former chairman of Nissan Motor Co., center, sits in a taxi as he leaves his lawyer's office in Tokyo, Japan, on Wednesday, March 6, 2018.

Ousted Nissan Motor boss Carlos Ghosn left prison on a $9 million bail on Wednesday, slipping past a throng of reporters in a blue cap and surgical mask, after vowing to mount a defence against financial misconduct charges that he has called "meritless."

Surrounded by security guards and dressed in a workman's uniform and glasses, Ghosn was virtually unrecognizable from his usual suited self as he left Tokyo Detention House, where he was confined to a small cell with no heating for more than 100 days.

The once-feted executive got into a small workvan parked just off the facility's front entrance. Public broadcaster NHK later showed the vehicle exiting the facility grounds, where hundreds of journalists, photographers, and TV crews have been camped, some even overnight.

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 that 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.