All eyes are on Prime Minister Shinzo Abe's ruling Liberal Democratic Party, its coalition partner Komeito and like-minded parties and whether they will gain a two-thirds majority in the House of Councillors.
In a poll last week, 41 per cent said they disapproved of Abe's economic policies, but support his Liberal Democratic Party (LDP), a less-than-resounding 37 per cent, far outpacing 11 per cent for the Democratic Party. That victory will bolster Abe's grip over the conservative party that he led back to power in 2012 promising to reboot the economy with hyper-easy monetary policy, fiscal spending and reforms.
"I have two more years to my term (as LDP president) and this is a goal of the LDP, so I want to address it calmly", Abe said.
The ruling coalition, which now holds 136 seats, appears to have brushed off a challenge from an alliance of opposition parties that had sought to unify the anti-government vote by avoiding running candidates against one another in many districts. But that has not weakened Abe in recent elections, although he has made clear that he is eager to restart reactors that were idled after the nuclear disaster, the worst since Chernobyl, and make atomic energy a Japanese export.
His minister for Okinawa, Aiko Shimajiri, lost her seat, along with Justice Minister Mitsuhide Iwaki.
Media surveys have shown the ruling bloc is set to exceed Abe's target of 61 seats while his LDP could win a majority on its own for the first time since 1989. Speculation has also emerged that Abe might replace Finance Minister Taro Aso, 75.
It remained unclear now that whether the ruling camp that groups LDP and the Komeito, as well as other two small opposition parties could win together two-thirds majority in the chamber so as to launch a Constitution amendment motion in the future. Its admirers consider it the source of post-war peace and democracy.
But any legislation that mustered the two-thirds majorities needed to pass both houses would face another hurdle in the form of a national referendum.
While Abe has long advocated constitutional change, and has already reinterpreted pacifist Article 9 to allow Japan's armed forces to defend other countries in some circumstances, it is unclear when - or even if - he will move to do so. "It doesn't want change", he said.
Shinichi Nishikawa, professor of political science at Meiji University in Tokyo, said the result, though undeniably a win, was no mandate.