Japanese voters were casting ballots on Sunday in an election expected to hand Prime Minister Sanae Takaichi a resounding win, although record snowfall blanketing parts of the country could keep some voters at home.

The conservative coalition of Takaichi, the nation's first female leader, is predicted to win around 300 of the 465 seats in the lower house of parliament, according to multiple opinion polls, a large gain from the 233 it is defending.

If the coalition of Takaichi's Liberal Democratic Party with the Japan Innovation Party, known as Ishin, wins 310 seats, it would be able to override the upper chamber, where it does not have a majority.

She has vowed to step down if the coalition loses its majority.

Takaichi, 64, who became prime minister in October after being selected LDP leader, sought a mandate from voters in a rare winter election as she rides ⁠a wave of popularity.

Her straight-talking style and image as a hard worker has won her support around the country, especially with younger voters.

"If Takaichi wins big, she will have more political room to follow through on key commitments, including on consumption-tax cuts," said Seiji Inada, managing director at FGS Global, a consultancy.

"Markets could react in the following days, and the yen could come under renewed pressure."

She has promised to suspend the eight percent sales tax on food for two years to help households cope with rising prices, partly driven by the yen's sharp fall.

Takaichi has generated a social media-led wave, mostly among younger voters, of a Sanae-mania called "sanakatsu" for products she uses, such as her handbag and the pink pen she scribbles notes with in parliament.

A recent opinion poll found voters under 30 favouring her by more than 90 percent.

That young cohort, however, is less likely to vote than the older generations that have long been the bedrock of LDP support.

Of the 465 seats in the House of Representatives, 289 will be elected from single-member districts and 176 through proportional representation in 11 regional blocs.

On Thursday, Takaichi received the endorsement of US President Donald Trump, a signal that may appeal to right-leaning voters, but could also put off some moderates. (Reuters/Xinhua)