Former Nissan Chairman Carlos Ghosn is preparing for a courtroom battle: File picture: Kin Cheung / AP Photo.

Tokyo - Motonari Ohtsuru, widely reported to be Carlos Ghosn's Japanese defence attorney, should be familiar with the tactics of the prosecution - he used to run the elite unit investigating the tycoon.

As a prosecutor, the bespectacled 63-year-old with floppy greying hair earned the soubriquet "the breaker" as he was so good at extracting confessions from suspects.

Considered a straight-shooter, he also became affectionately known as "Mr Square" as he was so straight-laced even in a profession known for its seriousness.

Being a prosecutor was always Ohtsuru's dream job and he rose up the ranks to become chief of a special squad in the Tokyo District Public Prosecutors Office, which probes the biggest financial cases - including Ghosn's.

After his appointment in 2005, he vowed to work to bring white-collar criminals to heel, spurred on by the sense of injustice felt by the working class.

At his inaugural news conference, Ohtsuru told reporters he wanted to "prosecute cases that anger honest workers and make them wonder 'How come this is allowed?'."

Ohtsuru, in a past article on the justice ministry website explaining his job, pledged to devote his team to defending people who play by the rules.

"We must not accept a society in which unfair behaviour triumphs and outdoes people who earn a living by the sweat of their brow or who lost their jobs in corporate restructuring, and companies that follow the law," Ohtsuru wrote.

However, he was not totally without sympathy for the people he prosecuted.

"Many people involved in crimes are hard-working salarymen. It sometimes occurred to me that I'd have done the same if I had been in their position," the Mainichi Shimbun daily quoted him as saying in 2005.

"I don't want to brag 'that was my case' as I think about the people involved."

As the boss of the special unit, he led investigations into major cases including an accounting fraud at rising Internet firm Livedoor and insider trading by a star fund manager in the 2000s.

But after three decades as a prosecutor, he switched sides in 2011 to become a defence lawyer.

Although he has taken on some of Japan's most high-publicity cases, Ohtsuru himself keeps a low media profile and little is known about his personal life except that he has a son and a daughter and a penchant for the saxophone.

Despite numerous calls, Ohtsuru's office declined to confirm his appointment but several Japanese media have reported that he will form part of the defence team.

- High profile acquittals -
Meanwhile, fellow Nissan executive Greg Kelly has hired Yoichi Kitamura, a lawyer who made his name defending influential politician Ichiro Ozawa when he was accused of breaking political fundraising laws.

Ohtsuru was one of the investigating prosecutors in that case meaning that lawyers for the two Nissan executives will have experience fighting against each other.

Kitamura has experience of winning high-profile acquittals.

He represented Takeshi Abe, a former leading authority on haemophilia, who was indicted in 1996 for allegedly using blood products knowing they could be tainted with the HIV virus.

In contrast, three former presidents of a drug company that sold contaminated blood were handed prison terms.

He also won a not-guilty verdict in 2003 for Kazuyoshi Miura, a Japanese businessman accused of killing his wife in the 1980s in Los Angeles.

Ghosn and Kelly stand accused of under-reporting the former Nissan boss's compensation to the tune of $44 million over five years. 

According to local media, both men deny the allegations.

Agence France-Presse