Japan is set to choose its fourth PM in five years - who could be next?

Japan's Prime Minister Shigeru Ishiba has announced his resignation after less than a year in the role - following two crushing election losses in mid-term elections.

His resignation came a day before opponents in his Liberal Democratic Party (LDP) were expected to vote him out.

His departure sets the stage for yet another ruling party leadership contest in Tokyo, the third in five years. That is apart from two national elections - neither of the winners completed their term.

But the country's future leader now faces a daunting task - balancing fraught US-Japan relations, rising inflation and a cost of living crisis, and a government that has lost its majority in both houses of parliament.

In 2020, Yoshihide Suga - who was previously the party's Chief Cabinet Secretary - stepped up to the role after the surprise resignation of the late Shinzo Abe, who had stepped down due to health issues.

After just a year in power, Suga resigned due to plummeting polls - and was replaced by Fumio Kishida, who then went on to win the election late in 2021.

But Kishida didn't last long either - his popularity plunged in the wake of a corruption scandal involving the LDP, rising living costs and a slumping yen.

And in 2024, he was replaced by Ishiba - who announced plans for a snap election just days after being elected, saying it was "important for the new administration to be judged by the people as soon as possible".

And judge him they did.

Many in the electorate were still furious over the corruption scandal that implicated senior members of the LDP, and were struggling to deal with rising inflation and a cost of living crisis. They delivered the LDP its worst result in over a decade and caused it to lose its single-party majority in the powerful lower house.

Earlier this year, the LDP suffered another defeat in the upper house parliamentary elections where it also lost its majority.

Ishiba resisted calls for him to step down at first, saying he needed to take responsibility for the LDP's losses and to deal with a trade deal with Washington.

But on Sunday - ahead of an internal leadership vote that could have forced him out - he bowed out, announcing his resignation.

"Voices had been mounting from within the party that the PM must take responsibility... [and] the writing was on the wall," said Tomohiko Taniguchi, a specially appointed professor at the University of Tsukuba and previously a special advisor to the late PM Shinzo Abe.

"So rather than waiting to endure public humiliation, Ishiba chose to step down," said Dr Taniguchi.

The LDP vote is expected in early October, with the winner almost certain to become prime minister.

No one has announced their intention to run, but there are three names that have emerged as possible contenders.

They are: Shinjiro Koizumi, the agricultural minister and son of a popular former prime minister; Yoshimasa Hayashi, the chief cabinet secretary; and Sanae Takaichi, who would be Japan's first female prime minister if she won.

All three had come up against Ishiba in the previous presidential race in 2024 - with Takaichi initially emerging as the strongest candidate in the first round of votes.

However, Takaichi - a close ally to Abe - was later overtaken by Ishiba.

The 64-year-old is a hardline conservative and is known to oppose same-sex marriage. Her positions on women's issues are in line with the LDP's policy of having women serve in traditional roles.

There's also 44-year-old Koizumi, the son of Junichiro Koizumi who was hugely popular when he served as prime minister from 2001 to 2006.

The fresh-faced younger Koizumi is media-friendly and popular online, where he is known for posting cat photos.

Then there's 64-year-old Hayashi, who acts as the government's top spokesperson in his pivotal role as chief cabinet secretary.

"You have an extreme set of candidates where one is very conservative, one is sort of an untested politician," said Dr Taniguchi. "And then there's Hayashi, someone who is not so flamboyant but more experienced and tested."

Other names that have been floated include former foreign minister Toshimitsu Motegi and former economic security minister Takayuki Kobayashi.

The new leader faces the challenge of bringing together a weakened party - and someone who can bring back voters to the LDP.

Japan is currently seeing a drift towards the far-right, with the nationalist Sanseito emerging as one of the biggest winners of Japan's recent upper house parliamentary election.

A large part of Sanseito's voter base were conservative voters that were drawn away from the LDP.

"Prime Minister Ishiba was considered not conservative enough by many supporters of Abe," Jeffrey Hall, a lecturer at Kanda University of International Studies, had earlier told the BBC.

"They think that he just doesn't have the nationalistic views on history, he doesn't have the strong views against China that Abe had."

So many turned to parties like Sanseito as a result.

"The fact that they succeeded in getting more votes shows the frustration of voters who would have ordinarily supported the LDP, but chose to leave and go to a party that is newly formed and yet to be tested," said Dr Taniguchi.

"The biggest task for the next leader of the LDP would be to bring back these voters."

It also comes as the country is dealing with a rising cost of living crisis amid a weakened yen.

"Japanese people are not accustomed to inflation so even a small amount feels shocking. For many ordinary voters, Japan just feels like its becoming a poorer country - prices are rising but wages are not going up, and with the yen being so weak, those going abroad would find everything so expensive," said Professor James Brown of Temple University Japan.

The next PM will also have to navigate Tokyo's tricky relationships with its neighbours.

Earlier last week, China celebrated its "Victory Day" parade - marking 80 years since it defeated Japan at the end of World War Two - which was attended by leaders such as North Korea's Kim Jong Un and Russia's Vladimir Putin.

"You're seeing three threatening neighbours, including a nuclear armed state, and a recent celebration [in China] on its victory over Japan," said Prof Brown.

"Whether the leader is more nationalistic like Takaichi or next-generation-minded like Koizumi... the endurance of trilateral cooperation among Tokyo, Washington, and Seoul will be closely watched after Xi, Putin, and Kim so visibly displayed solidarity in Beijing," said Leif-Eric Easley, a professor at Ewha University in Seoul.

Even Japan's relationship with its long-term ally the US can get tense.

US President Donald Trump had earlier this year demanded that Tokyo pay more for stationing American troops in Japan.

"[Amid all this happening], there's a bit of despair in the public. There's no great hope that a different leader would make any major difference. For many people they think it's just the same old story, just with a different LDP leader," says Prof Brown.

Japan has over the last two decades seen more than 10 prime ministers.

This is due in part to it being a "one-party democracy", says Prof Brown.

"In terms of government, it's really only ever been the LDP - so that means the main political competition comes from within the party, rather than from external parties.

"So within the LDP there are vicious struggles within different factions - they all want their own faction to get the top job.

"So even though you might be selected as leader, as soon as you're in office, you have dozens of people manoeuvring to try to get you out again."

Whoever takes up the leadership position will almost be drinking from a "poisoned chalice", adds Prof Brown.

As attention now turns to Ishiba's replacement, many are also waiting to see if the next leader can break Japan's cycle of short-lived prime ministers.