by Kyoko HASEGAWA

(AFP) Tokyo governor Yuriko Koike won a landslide victory to secure a third term, official election results showed Monday, in a rare triumph for a woman in Japan's male-dominated politics.

The outcome from Sunday's vote is also a relief to unpopular Prime Minister Fumio Kishida's ruling Liberal Democratic Party (LDP), which backed Koike despite her not being a member.

Koike, 71, a former minister and television anchor who has governed one of the world's biggest cities since 2016, garnered 42.8 percent of votes, results showed.

Her nearest rival was independent candidate Shinji Ishimaru, 41, the former mayor of Akitakata in western Japan, who secured 24.3 percent to pull off a surprise second place.

Koike's main challenger had been thought to be another woman -- former opposition lawmaker, model and TV anchor Renho, 56, who goes by one name -- but she garnered just 18.8 percent.

Koike declared victory late Sunday, vowing to strengthen Tokyo's welfare, economy and natural disaster management, while acknowledging challenges like inflation and Japan's low birth rate.

"With Tokyoites' strong support, I was assigned to lead this great city," Koike told supporters in the megacity of 14 million people.

"I have to upgrade efforts of Tokyo's reforms, and as I appealed in my election campaign, I will protect Tokyo residents' lives and livelihoods," she said.

- Subsidised epidurals -

Japan has never had a woman prime minister and a large majority of lawmakers are men, although Tokyo accounts for a 10th of the national population and a fifth of the economy.

The Tokyo vote comes after new government data showed the birth rate hit a record low of 1.20 last year, with Tokyo's figure 0.99 -- the first Japan region to fall below one.

Koike and her major rivals pledged to expand support for parenting, with the former promising government subsidies for epidurals.

"After having their first child, I hear people say they don't want to experience that pain again," Koike said during the election campaign.

"I want people to see childbirth and raising children as a happiness, not a risk," she said.

A record 56 people were standing in the election, not all of them serious, with one dressing as "The Joker" and calling for polygamy to be legalised.

Others campaigned for more golf, poker -- or just to advertise their premises in Tokyo's red-light district.

The LDP has governed Japan almost uninterrupted since World War II but the party's popularity rating has sunk to around 20 percent, partly due to a political funds scandal.

Kishida, 66, will face the LDP leadership election later this year before a national vote due by late 2025.