Sanae Takaichi has won a historic vote to become Japan's first female prime minister
The 64-year-old conservative is known as Japan's "Iron Lady" - she's an admirer of the UK's former PM Margaret Thatcher
This is her third attempt at becoming Japan's leader, and she's the fourth PM in five years from her scandal-hit party, the LDP - here's why Japanese PMs change so often
She belongs to the LDP's hardline wing and is a protege of the late former PM Shinzo Abe
Trump had earlier hailed her as a "highly respected person of great wisdom"
Now that she's elected, Takaichi's challenges will include fixing a sluggish economy, navigating a rocky US-Japan relationship and uniting a divided ruling party
The moment Sanae Takaichi wins Japan's lower house
Shaimaa Khalil
Tokyo correspondent
This is a historic moment - the first time Japan has put a woman in the top job.
Many observers told me that part of the reason for the right wing leader's ascension is the governing party wanting to appeal to its conservative base, some of whom had switched to the more right-wing Sanseito party after it made significant gains in the recent upper house elections.
Lawmakers in the Lower House have voted for Takaichi to become Japan's next Prime Minister.
She got 237 votes - more than what's needed for a simple majority.
The voting has ended in the Upper House as well, and now vote counting is under way.
A reminder that the critical vote for Takaichi is the Lower House vote.
We're still waiting for the results of the vote in the Lower House, which is considered the more important of the two parliamentary houses.
While separate votes are held in the two houses, the Lower House's result takes precedence over the Upper House.
So if Takaichi wins the vote in the Lower House, her path to the premiership is clear.
Voting has started in the Upper House of Japan's parliament, which has 248 seats and is considered less powerful than the Lower House.
Takaichi will need 124 votes to win a majority here. She needs to win the majority in both houses of parliament.
A reminder that you can watch the vote live by clicking on the play button at the top of the page.
Voting has concluded in the Lower House, and counting is now underway. It will take about 15 minutes to count all the votes.
Sanae Takaichi has just cast her vote, to the applause of some lawmakers in the background.
Japan's ruling Liberal Democratic Party has been going through a rocky patch in recent months. Here's look at the key events that led us here:
Shaimaa Khalil
Tokyo correspondent
Lawmakers have begun voting - we will soon see if Takaichi is confirmed as prime minister.
Takaichi needs a majority in both chambers to win - 233 in the lower house and 124 in the upper house. After her deal with the Japan Innovation Party, she is two votes short of a majority.
If no candidate wins a majority in the first round, a second round of voting between the two leading candidates will be held at 14:30 local time (05:30 GMT).
Voting is now under way in the lower house of parliament.
A reminder that you can watch the vote live by clicking the play button at the top of this page.
Voting in parliament is expected to start in the next half hour. Click here or the button at the top of this page to watch live.
Yvette Tan
BBC News
Over the last two decades, Japan has seen more than 10 prime ministers.
In fact, one expert likens taking up the country's top job to drinking from a "poisoned chalice".
But why does the country keep changing leaders? It's due in part to it being a "one-party democracy", says Prof James Brown of Temple University Japan.
The LDP's grip on the country's politics 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."
Mariko Oi
Presenter, Asia Specific podcast
For more than a decade, I have made over a dozen BBC programmes about Japan's effort to increase the number of female leaders.
Having grown up in Japan, I knew too well that changes happen slowly in my home country.
But even then, I felt frustrated as various political parties asked high-profile female candidates with no political experience such as celebrities to run for office. I thought it should be the best candidate regardless of their sex who should win.
But my school friend who is now a lawmaker in Tokyo told me an anecdote that changed my views slightly.
When Risa Kamio was first elected, she was told to clear her schedule for two straight days as they were expected to continue their meeting overnight. She was a working mother so she and other female lawmakers pushed back.
Risa told me that having more working mothers helped, and several years later, she told me that they no longer have overnight meetings.
Shaimaa Khalil
Tokyo correspondent
Image source, ReutersA big fan of the UK’s first woman PM Margaret Thatcher, Sanae Takacihi has always wanted to be the "Iron Lady" of her country.
Takaichi has long been a staunch conservative - opposing same-sex marriages and standing against legislation that would allow married couples to have separate surnames, preventing many women from keeping their maiden names.
She also takes a hardline stand on immigration. She has said she would "clamp down on rule-breaking visitors and immigrants" who have come to Japan in record numbers.
Image source, ReutersBorn in Nara Prefecture in 1961, Takaichi's father was an office worker and her mother a police officer. Politics was far removed from her upbringing.
Once an avid heavy metal drummer, she was famous for carrying many sticks because she would break them during intense drumming.
Her political inspiration came in the 1980s, during the height of US-Japan trade friction.
She won a parliamentary seat with the LDP in 1996. Since then, she has been elected as an MP 10 times, losing only once, and built a reputation as one of the party's most outspoken conservative voices.
After two failed attempts, she was elected the LDP's leader, which paved the way for Tuesday's vote where she is widely expected to confirmed as prime minister.
Peter Hoskins
Business reporter, Singapore
Image source, ReutersJapanese stocks have hit new record highs on expectations that Takaichi is set to be confirmed as the country's new prime minister.
The benchmark Nikkei 225 share index jumped by about 1.5% to over 49,900.
Investors have welcomed her plans to to increase government spending, cut taxes and pressure the central bank to slow interest rate rises.
But some are concerned that higher spending and lower tax revenue will mean more government borrowing.
Shaimaa Khalil
Tokyo correspondent
Image source, ReutersHere's what we're expecting in the coming hours, with lawmakers in both the Upper and Lower Houses set to vote for a prime minister.
233 votes are needed for a majority in the 465-seat Lower house, while 124 votes make the majority in the 248-seat Upper house.
The first round of voting begins at 13:30 local time (04:30 GMT).
If a candidate secures majorities in the first round, then they're elected prime minister.
If they don't, it goes to a run-off between the top two candidates. The one with the most votes wins. The second round of voting is scheduled for 14:30 local time (05:30 GMT).
Once the parliament chooses its new prime minister, the new government will announce its cabinet members. They will then head to the imperial palace for an attestation ceremony and they will have first cabinet meeting.
A press conference for the new prime minister is not expected until late tonight.
Good afternoon/morning from our newsrooms in Tokyo and Singapore. We are watching what is poised to be a historic vote in Japan, where lawmakers are expected to shortly elect the country's first female prime minister.
Sanae Takaichi is set to become PM after her party, Japan's ruling LDP, stitched up a late night deal with the Japan Innovation Party (JIP), bringing her to within two votes of the prime minister's office.
We will be bringing you all the latest updates on the vote, the result and all the reactions - stay with us.