TOKYO - Japan dissolved the Lower House of Parliament on Thursday (Sept 28), paving the way for snap polls on Oct 22.
Campaigning for the election will start on Oct 10.
Opposition lawmakers skipped the parliament session en masse on Thursday to protest against the snap poll, which is being held more than a year before it is due.
Prime Minister Shinzo Abe said at the start of a Cabinet meeting on Thursday morning that the snap poll will be an opportunity for a thorough debate on policy issues.
"Our job, as the Liberal Democratic Party (LDP)... is to explain our policies and produce results," he said.
Voting is not compulsory, and is open to Japanese citizens aged 18 and above.
Although his support ratings had dropped below 30 per cent two months ago over two cronyism scandals, Mr Abe, 63, and his LDP had been widely expected to claim a routine victory, despite potential voter fatigue at yet another election. For Tokyo residents at least, this would be their fourth election since July last year.
But that was until Ms Koike, 65, sent shockwaves nationwide with her surprise announcement on Monday that she would herself be helming the new Kibo No To, instead of playing a supporting role in its formation.
She intends to field at least 100 candidates nationwide, which by itself will not allow the Kibo No To to unilaterally form the government – this will require winning at least 233 out of the 465 seats up for grabs.
Ms Koike, with her disarming charisma and media savviness, is a widely popular maverick politician who has twice taken on the LDP - and won. She was an eight-term Lower House lawmaker until July last year, when she quit to run for Tokyo governor against the LDP-backed candidate.
In July this year, she led a new party, the local Tomin First No Kai (Tokyoites First), to a resounding victory over the LDP. Tomin First fielded 50 candidates and won 49 seats, ousting more than half of the LDP's candidates along the way.
This time round, she will not be throwing her hat into the ring as a candidate, but will stump for her candidates, as she said on Wednesday.
Media polls over the weekend had shown Mr Abe was likely to claim a resounding victory - but with the assumption that Ms Koike would not be front and centre of the campaign.
Mr Abe has couched the election - which was due only in December 2018 - as necessary on two fronts: First, a referendum on how the projected increase of five trillion yen (S$60.5 billion) in tax revenue from a slated tax hike in October 2019 from 8 per cent to 10 per cent would be spent. As much as 80 per cent of it was to be used to pay down debt and 20 per cent on social security issues, but Mr Abe is now championing a 50-50 split.
Mr Abe is also seeking a public mandate on his government's strategy of continuing to up the pressure on a belligerent North Korea.
But experts and laymen alike have accused him of using these reasons as an excuse to pull the wool over their eyes, and said Mr Abe was just capitalising on a rebound in his support ratings to seek political legitimacy - and another four years in power.