TARO ASO

The 79-year-old Finance Minister, who also doubles as Deputy Prime Minister, has been a core member of Mr Shinzo Abe's administration.

In 2008, Mr Aso was elected Liberal Democratic Party (LDP) leader and hence premier, in hopes that he could revive the long-dominant party's fortunes.

Instead, the LDP was ousted in a historic election defeat in 2009, languishing in the opposition for the next three years.

The grandson of a former premier, Mr Aso mixes policy experience with a fondness for manga comics and a tendency towards gaffes.

SHIGERU ISHIBA

A hawkish former defence minister and rare LDP critic of Mr Abe, Mr Ishiba, 63, regularly tops surveys of lawmakers whom voters want to see as the next premier, but is less popular with the party's lawmakers.

The soft-spoken security maven has also held portfolios for agriculture and reviving local economies.

He defeated Mr Abe in the first round of a party presidential election in 2012, thanks to strong grassroots support, but lost in the second round when only MPs could vote.

Then, in a 2018 party leadership poll, Mr Ishiba lost heavily to Mr Abe.

He has criticised the Bank of Japan's (BOJ) ultra-low interest rates for hurting regional banks and called for higher public works spending to remedy growing inequality.

FUMIO KISHIDA

Mr Kishida, 63, served as foreign minister under Mr Abe from 2012 to 2017, but diplomacy remained mainly in the Prime Minister's grip.

The low-key lawmaker from Hiroshima has been widely seen as Mr Abe's preferred successor but ranks low in voter surveys.

Mr Kishida hails from one of the party's more dovish factions and is seen as less keen on revising the post-war Constitution's pacifist Article 9 than Mr Abe, for whom it is a cherished goal.

The BOJ's hyper-easy monetary policy "cannot go on forever", Mr Kishida has said.

TARO KONO

The 56-year-old Defence Minister has a reputation as a maverick but has toed the line on key Abe policies, including a stern stance in a feud with South Korea over wartime history.

Educated at Georgetown University and a fluent English speaker, he previously served as foreign minister and minister for administrative reform.

He has differentiated his conservative views from those of his father, former chief Cabinet secretary Yohei Kono, who authored a landmark 1993 apology to "comfort women", an euphemism for women forced to work in Japan's wartime military brothels.

YOSHIHIDE SUGA

Mr Suga, 71, a self-made politician and loyal lieutenant since Mr Abe's troubled term as premier in 2006 and 2007, was among a band of allies who pushed Mr Abe to run again for the top post in 2012.

Back in office, Mr Abe tapped Mr Suga as chief Cabinet secretary, acting as top government spokesman, coordinating policies and keeping bureaucrats in line.

Talk of Mr Suga as a contender surfaced in April last year after he unveiled the new imperial-era name "Reiwa", for use on Japanese calendars after the enthronement of the new emperor.

His clout was dented somewhat by scandals that toppled two Cabinet ministers close to him last October.

SHINJIRO KOIZUMI

The name of Mr Koizumi, 39, now Environment Minister and the son of charismatic former premier Junichiro Koizumi, is often floated as a future premier, but many consider him too young.

He shares some of Mr Abe's conservative views and has paid his respects at Tokyo's controversial Yasukuni Shrine for the war dead.

Mr Koizumi has projected a reformist image on the basis of efforts to cut Japan's backing for coal, the dirtiest fossil fuel, but has typically taken care not to offend party elders.

TOSHIMITSU MOTEGI

Currently Foreign Minister, Mr Motegi, 64, previously served as economy minister, facing off with US Trade Representative Robert Lighthizer in tough negotiations.

He also served as trade minister under Mr Abe when the latter returned to power in 2012, tackling talks on the Trans-Pacific Partnership free trade pact.

Educated at the University of Tokyo and Harvard, Mr Motegi was first elected to the Lower House in 1993 from the then opposition Japan New Party and joined the LDP in 1995.

KATSUNOBU KATO, YASUTOSHI NISHIMURA

As Health Minister, Mr Kato, 64, was in the limelight in the early days of Japan's coronavirus outbreak, but then Economy Minister Yasutoshi Nishimura, 57, a former trade official, emerged as the point person on virus policy.

In 2015, Mr Kato, a father of four, was handed the portfolio for boosting Japan's rock-bottom birth rate, a task that met little success.

He is a former official of the finance ministry.

SEIKO NODA

Ms Noda, 59, has made no secret of her desire to become Japan's first female premier. An Abe critic, the former internal affairs minister, who also held the portfolio for women's empowerment, fell short of backing to join the race for party leader in 2018.

REUTERS