A doctor is attending to the 64-year-old, who is exhausted from the long detention and interrogations, said his lawyer Motonari Otsuru.
Ghosn has already been indicted once, over allegations he under-reported his salary over five fiscal years to the tune of ¥5 billion (US$46 million) in official documents to shareholders.
The ousted Nissan Chairman was indicted Friday for acts including temporarily transferring personal trading losses to Nissan in 2008, as well as for understating his compensation for three years through March 2018.
A prosecutor's office spokeswoman said the charges against Ghosn carry a maximum prison sentence of 15 years.
At the court, Ghosn said his actions were backed by managers inside the company as well as external lawyers.
Ghosn's prolonged detention has put the spotlight on Japan's justice system, which has come in for some global criticism.
The second charge against him alleges that the under-reporting continued for another three years. The open hearing on Tuesday, which drew worldwide attention, was his first public appearance since his arrest on November 19. The former auto tycoon has been charged with aggravated breach of trust, and with violating a financial law by underreporting his compensation. Nissan said it regretted any concern caused to its stakeholders.
Nissan and Renault stay together The legal woes have strained the partnership between Nissan and Renault, the French auto maker that owns over 40 per cent of Nissan. The sum of the remuneration that was allegedly underreported totals about ¥9 billion ($83 million).
He was served with a fresh arrest warrant on December 21 for allegedly shifting a private currency swap contract with losses worth 1.85 billion yen to Nissan in October 2008 and causing damage to the company by having it pay $14.7 million to a Saudi businessman, who guaranteed credit for Ghosn, in the following years.
"I recently learned that my husband is suffering from a high fever at the detention center in Tokyo, but my information is limited to news reports as no one in his family has been allowed to contact him since November 19", the statement by Ghosn's wife Carole said.
On Wednesday, the Tokyo District Court rejected a request filed by Ghosn's defense counsel to end his detention following his arrest on allegations of financial misconduct.
Under Japan's Code of Criminal Procedure, prosecutors can continue holding an accused person in custody if they indict the suspect within the detention period following an arrest.
It is uncommon for defendants in Japan who deny charges to be granted bail ahead of trial, a practice that has drawn widespread criticism, including from Ghosn's defence team. Prosecutors have the right to appeal to a court to extend the detention.
Ghosn, 64, appeared in court Tuesday for the first time since his arrest, looking thinner and grayer.
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