Tokyo (AFP) - A seasoned defence geek and a nationalist who would be Japan’s first woman prime minister will go head-to-head in the final round of a ruling party leadership vote on Friday, the official count showed.

Liberal Democratic Party (LDP) lawmakers and party members will choose between former defence minister Shigeru Ishiba and hawkish Sanae Takaichi – a rare prominent woman in Japanese politics – as the country’s next premier.

Whoever wins must face down regional security threats, from an increasingly assertive China and its deepening ties with Russia to North Korea’s banned missile tests.

At home, the leader will be tasked with breathing life into the economy, as the central bank moves away from decades of monetary easing that has slashed the value of the yen.

Ishiba, 67, has come close to the top job before, including in 2012 when he lost to nationalist Shinzo Abe, Japan’s longest-serving leader who was later assassinated.

The military model-maker with an affinity for 1970s pop idols says his experience tackling tough social issues, such as agriculture reforms, makes him qualified for the job.

As scandals fuel public discontent with the LDP, “the tide is in favour of Ishiba and his ‘fair and square’ attitude,” said Yu Uchiyama, a University of Tokyo politics professor.

Economic Security Minister Takaichi, 63, is a former Abe mentee opposed to changing the law to allow separate surnames for married couples.

She regularly visits Tokyo’s Yasukuni war shrine, a flashpoint in relations with South Korea and China.

“Japan is completely looked down on by China,” she told Fuji Television when asked about the first confirmed incursion by a Chinese military aircraft into Japan’s airspace, which happened in August.

Naofumi Fujimura, a professor at Kobe University’s Graduate School of Law, said that while Takaichi currently needs the support of the LDP’s right-wingers, she could prove “more centrist, or more pragmatic” as prime minister.

- ‘Concerned about China’ -

In the first round of voting, a record nine candidates had been in the running after the LDP’s long-powerful factions disbanded earlier this year over a funding scandal.

Because the conservative party holds a parliamentary majority, the winner is certain to become prime minister, and will likely call a snap election to shore up their mandate.

On the streets of Tokyo, 72-year-old retiree Yasumi Fujino told AFP she was “concerned about China” and hoped “the next person will focus on diplomacy”.

But “I do not agree with Takaichi… she’s like the number one follower of prime minister Abe”, she said.

LDP presidents are in office for three years and can serve up to three straight terms. Unpopular Prime Minister Fumio Kishida is not running for re-election.

In third place behind Ishiba and Takaichi was former environment minister Shinjiro Koizumi, a keen surfer whose father was prime minister in the 2000s.

Critics had said he was too inexperienced to lead the country.

Whoever emerges victorious on Friday will be formally elected by parliament on October 1.

The LDP has governed Japan almost uninterrupted for decades, with the main opposition parties rarely seen as viable alternatives.

During his term, Kishida has taken steps to double Japan’s defence spending, opening the door for military exports as the LDP seeks to revise the pacifist post-war constitution.

He welcomed Ukrainian President Volodymyr Zelensky to a G7 summit in Hiroshima and has strengthened Japan’s often testy ties with its neighbour South Korea.

But his rule was also tarnished by scandals, voter anger over rising prices and sliding poll ratings.