Japanese voters hit the polls on Sunday with Prime Minister Fumio Kishida hoping to win over a pandemic-fatigued public as his long-ruling conservatives battle to preserve their commanding majority in parliament.

Kishida became leader of the Liberal Democratic Party a month ago after Yoshihide Suga resigned just a year into the job, partly due to public discontent over his response to the Covid-19 crisis.

Despite a steep drop in cases, the LDP -- which has held power almost continuously since the 1950s -- is likely to lose seats in parliament's lower house, analysts say.

Even if Kishida wins, a poor showing could threaten his longevity as leader of a country with a long history of revolving-door premierships.

The soft-spoken moderate, 64, has pledged to issue a fresh stimulus package worth tens of trillions of yen to counter the impact of the pandemic on the world's third-largest economy.

He has also outlined plans to combat inequality heightened by the business-friendly policies of Suga and his predecessor Shinzo Abe, saying he will distribute wealth more fairly under a so-called new capitalism, although details so far remain vague.

Voters in Tokyo told AFP the pandemic was an important factor in their decision.

"The economy is suffering because of the coronavirus, so I compared the politicians' responses," said Chihiro Sato, 38, a housewife and mother of a toddler.

But engineer Hiroyasu Onishi, 79, said he was more concerned by "the military threat from China".

Japan's 106 million voters have "struggled to get excited about the new prime minister", said Stefan Angrick, a senior economist at Moody's Analytics.

"Kishida will need to convince the public and younger members of his party that continuity does not mean status quo, but rather maintaining what has worked and improving on what has not."

- Revolving-door risk -

Kishida has not enjoyed a political honeymoon, with approval ratings around 50 percent, the lowest in two decades for a new administration in Japan.

He has set a comfortable target of winning 233 of the 465 lower-house seats -- a simple majority including lawmakers from the LDP's junior coalition partner Komeito.

However, such a result would be seen as a setback for the LDP, which previously held 276 seats on its own.

In recent decades, votes against the LDP have been split between multiple major opposition parties, but this time five rival parties have boosted cooperation in a bid to dent its stranglehold.

Nonetheless, the LDP enjoys "great advantages" with a strong network of supporters nationwide, said Michael Cucek, assistant professor of Asian studies at Temple University.

The LDP wants to put a tumultuous year behind it, but "the fact that they are still having to fight so hard is, for them, highly embarrassing", Cucek told AFP.

"If (Kishida) leads the party into a loss of seats, a clock starts ticking in the minds of his rivals in the party, saying 'maybe he is only a one-year prime minister'."

Only five politicians have hung on to the prime minister's office for five years or longer since World War II, including Abe, who was in power from 2012 to 2020 after a previous one-year term.

Turnout stood at 21.5 percent as of 2 pm on Sunday, down only slightly from the same time during the last general election in 2017, when overall turnout reached 53 percent.

As well as vowing to tackle the pandemic and working to boost the middle class, the LDP has said it will aim to increase defence spending to counter threats from China and North Korea.

Meanwhile, some opposition parties have emphasised their support for social causes that Kishida has so far distanced himself from, such as same-sex marriage and allowing married couples to have different surnames.

"I focused on the candidates' policies on same-sex marriage and LGBT issues. I have many friends in gay or lesbian couples. I hope public understanding on these issues will deepen," said 18-year-old Eko Nagasaki as she voted for the first time.