China-baiting former Tokyo governor Shintaro Ishihara on Tuesday threw his weight behind the political ambitions of an ex-military chief who was sacked after insisting Japan was not a World War II aggressor.

The acerbic Ishihara, 81, who was governor of Tokyo for 13 years to 2012, said he believed the next leader of the metropolis should be fellow hardline nationalist Toshio Tamogami, the onetime chief of staff of Japan's Air Self-Defence.

Tamogami was fired from the role in 2008 after he said Japan was an Asian bulwark against Western imperialism in World War II, rather than the nation responsible for continent-wide suffering.

The 65-year-old said Tuesday he believed that he should triumph in next month's gubernatorial race because of his experience in the military, which he said would need to play a central role in the aftermath of any big earthquake striking Tokyo.

"I made the decision because it's best for protecting Tokyo that I become the governor," the former general told reporters.

The job became vacant last month when Ishihara's hand-picked successor fell on his sword in a money scandal.

Ishihara's bid to buy the disputed Senkaku Islands during his tenure as Tokyo governor sparked a nosedive in relations with China, which claims them as the Diaoyus.

He was at the press conference to lend his support.

But the wizened former city boss, now a member of parliament, admitted Tamogami faced a "tough battle."

"This is a tokkotai (suicide attack) in a sense," Ishihara said, using an expression laden with connotations of the honour which Japanese Imperial troops were supposed to feel when sent off to battle.

"The man in this high position dares to join the battle with very little possibility of winning. I dearly hope people will share and understand the sense of duty and sense of crisis behind his decision."

Tamogami said Tokyo should educate youngsters to have "confidence and pride" in their country. Many on the right of Japanese politics express exasperation at what they say is the unfair characterisation of Japan as a bad country because of its behaviour in the first half of the 20th century.

Tokyo's gubernatorial vote on Sunday, February 9, comes after the humiliating resignation of Naoki Inose after he admitted receiving an undeclared $500,000 from a healthcare tycoon in the run-up to his election.

The forthright Ishihara is a detested figure in China because of his frequent outspoken remarks on the two countries' shared past.

His attempt to purchase the Senkakus sparked more than a year of heated confrontations between Beijing and Tokyo, which have been exacerbated by the nationalist stance of Prime Minister Shinzo Abe.

Other than Tamogami, Kenji Utsunomiya, a 67-year-old liberal lawyer who lost to Inose in the previous Tokyo election in 2012, has also put his hat in the ring.

Local media reports say the Tokyo chapter of the ruling Liberal Democratic Party plans to decide this week on a candidate to back.