Voting has closed in Japan’s parliamentary election, with exit polls suggesting Prime Minister Shinzo Abe will increase his majority.
About half the seats in the upper house of parliament were up for grabs.
Prime Minister Shinzo Abe is hoping for backing for his economic policies.
If he can achieve a two-thirds majority in the upper house, to match that in the lower house, he could also hold a referendum on constitutional change, easing constraints on military action.
Polling stations closed at 20:00 local time (11:00 GMT).
Mr Abe’s governing Liberal Democratic Party currently has 116 seats in the 242-strong upper house and can also count on 20 seats for its junior coalition partner, the Komeito party.
The BBC’s Stephen Evans, in Tokyo, says Mr Abe has fought his campaign on his economic record, but the sub-text of the election has been the power to amend the constitution.
Mr Abe is thought to want to change Article 9, the so-called pacifism clause which forbids Japan from fighting wars abroad – imposed by the US after Japan was on the losing side in World War Two, 70 years ago.
Some in Japan view the constraint as unfair, our correspondent says, and the rise of China has reinforced the view on the right that the clause should go.
The opposition has asked voters to reject any adoption of a more assertive military role.
Mr Abe has based his election campaign on his economic policies, although he admits himself that his Abenomics, aimed at ending debilitating deflation, are only “half done”.
This is the first nationwide election since the voting age was lowered from 20 to 18.