The potential contenders
Sign up now: Get insights on Asia's fast-moving developments
FUMIO KISHIDA
Mr Fumio Kishida, 64, is the only declared candidate and has already pledged to spend big if elected, promising a new stimulus package to counter the effects of the pandemic on the world's third-largest economy.
The soft-spoken politician is seen as "moderate and capable", making him a top pick for the premiership, according to Nihon University politics professor Tomoaki Iwai.
Although the former foreign minister is head of a Liberal Democratic Party (LDP) faction known for its dovish stance, his low-key presence and alleged lack of charisma could hamper his chances.
TARO KONO
Former defence minister Taro Kono has overseen Japan's vaccine roll-out, which began slowly but has picked up speed, with just under half of the population now fully inoculated.
The 58-year-old was once considered an ambitious and independent-minded political reformer, but has toned down his rhetoric in recent years.
Currently the Minister for Administrative Reform, Mr Kono - a fluent English speaker and keen Twitter user - served as foreign minister between 2017 and 2019.
He travelled extensively as Japan's top diplomat, but also oversaw the deterioration of ties with South Korea over unresolved wartime disputes.
SANAE TAKAICHI
Ms Sanae Takaichi, one of Japan's few prominent female politicians, is seen as a hard-right nationalist and has been forced to apologise for several gaffes over the years.
She is a regular visitor to Tokyo's controversial Yasukuni Shrine, which honours the war dead including war criminals, enraging South Korea and China.
A divisive figure within the party, the 60-year-old most recently served as minister for communications and internal affairs, vowing to tackle cyber bullying after the death of a reality show star.
During a previous stint as interior minister, she threatened to cut off TV news stations over perceived unfriendly coverage.
SHIGERU ISHIBA
Former defence minister Shigeru Ishiba is considered a military geek but is also a self-confessed fan of 1970s pop music.
The 64-year-old former banker is the scion of a political family and is seen as popular with the public. He is a strong orator with significant experience.
Seen as a hawk who wants to strengthen the role of Japan's Self-Defence Forces in the pacifist Constitution, Mr Ishiba has even mused over whether the country should reconsider its policy forbidding nuclear weapons on its soil.
He has served in several Cabinet posts, but he may struggle to win votes from his fellow ruling party lawmakers, partly because he once left the LDP.
HAKUBUN SHIMOMURA
LDP policy chief Hakubun Shimomura had said he would not challenge Mr Yoshihide Suga after the Prime Minister reportedly asked him to leave his powerful party post if he decided to run.
But with Mr Suga no longer in the picture, the 67-year-old former education minister could throw his hat in the ring.
Mr Shimomura has worked to plan Japan's Covid-19 countermeasures, with large swathes of the country under a virus state of emergency for most of this year.
Having lost his father when he was nine, he faced financial hardship growing up but won scholarships for his education.
SEIKO NODA
A critic of former prime minister Shinzo Abe, Ms Seiko Noda, 60, a former internal affairs minister, has held the portfolio for women's empowerment and is in favour of allowing married couples to keep separate family names.
She wanted to challenge Mr Abe for the LDP presidency in 2015 but fell short of the 20 backers needed to run.
Ms Noda has told LDP lawmakers that she wants to run in the party leadership race, according to broadcaster NHK.
AGENCE FRANCE-PRESSE, REUTERS
