Rikki Kersten is a Professor of Modern Japanese Political History at the ANU.

Shinzo Abe's Liberal Democratic Party may have scored a thumping win in Japan's half-upper house election on Sunday, but this will not translate into carte blanche for Abe's agenda.

Pundits have been quick to assume that a majority for the LDP-Komeito coalition in both houses of parliament will see Abe rush to implement his nationalist program of constitutional revision and a more muscular defence platform. But Abe's win carries a democratic deficit that will constrain his nationalist ardour.

The numbers go against Abe in several respects. The voter turnout of 52.61% is the third lowest in postwar history. Confronted with the reality of only one viable political force to support, close to half of the eligible electorate did not bother to go to the polls.

Unaffiliated voters conveyed a message too: among the 20.3% of people who declared no loyalty to any political group, 25% cast their vote for the LDP-Komeito coalition, but over 13% chose the Japan Communist Party instead. In the eyes of swinging voters, given that the Democratic Party of Japan continues to suffer electoral disdain for its ineptitude in government, the JCP is now the only identifiable entity that serves as a clear opposition to the ruling party.

In this light, the half upper house election emerges as a rebuke of one-party dominance, and a clear signal to the dispersed opposition forces that the country wants a viable opposition.

Other sets of numbers augur ill for Abe's claim of a mandate to implement his policy agenda. The unresolved issue of a gaping gerrymander has distorted the notion of representation to the point of collapse. Even as Abe claimed victory, lawsuits were filed in Japan's high courts to declare the result nullified on the grounds of unacceptable disparities in the value of votes – as much as 4.77 between the least and the most populated prefectures per elected representative.

Issue-specific polling reveals that support for Abe's LDP is selective. 'Abenomics' is the main driver of voter support for Abe, but the figures do not endorse Abe's program of constitutional revision if it includes diluting the pacifist clause. Many voters – just over a straight majority at last count – favour constitutional revision if it includes contemporary concerns such as human rights. But this surge dissipates when the substance turns to pacifism. The electorate is voting for economic recovery, not nationalist resurgence.

Logically, the two-house majority now enjoyed by the LDP-Komeito coalition suggests that almost anything is possible in terms of getting their legislative program through. But the Komeito is on record refusing to entertain revision of the constitution and Article 9. Without Komeito, Abe will need to cobble together an opportunistic coalition comprising the minor parties.

But the parliamentary numbers don't add up. The Restoration Party is now toxic after its figurehead Hashimoto made fatuous comments about 'comfort women' that saw even domestic opinion turn on him and his party. Your Party stepped away from supporting constitutional revision before the poll, and it continues to play the long game as far as political realignment is concerned. This leaves the DPJ, which remains a party divided against itself. A disintegration of the DPJ along policy lines is quite possible, but it is unlikely to deliver the 99 votes the LDP needs to trigger a referendum on constitutional revision (assuming the Restoration Party and Your Party play along).

The spectre of an ultranationalist turn in Japanese political life exists mainly in the dreams of Abe and his conservative supporters. Observers in China and the ROK tend to spotlight Abe's revisionist views, and his record of equivocation over apologies for war crimes provides oxygen for their misgivings. But Abe does not represent his nation when it comes to nationalist revival.

Photo by Flickr user CSIS.