Tokyo stocks rose 0.76 percent by the end of Thursday's morning session, boosted by optimism over the US economy and a weakening yen as speculation of more Bank of Japan easing grows.
The benchmark Nikkei 225 index added 72.37 points to 9,541.21, while the broader Topix index of all first-section shares gained 0.80 percent, or 6.24 points, to 788.10.
US stocks closed mostly higher overnight on hopes for progress in fiscal cliff negotiations and upbeat economic data.
The Dow Jones Industrial Average finished Wednesday up 0.64 percent at 13,034.49 after the Institute for Supply Management's November index on service sector activity rose, lending markets some support after the ISM's manufacturing index released earlier this week showed a monthly contraction.
"The overseas signals are positive while domestically, indications about the December 16 lower house election, which are showing a likely strong opposition Liberal Democratic Party victory (LDP), should send the market higher," said SMBC Nikko Securities general manager of equities Hiroichi Nishi.
Shinzo Abe, head of the main opposition LDP and widely tipped to become Japan's next prime minister, has vowed to pressure the Bank of Japan to launch more aggressive easing measures to boost the world's third-largest economy.
In currency trading, the dollar edged higher against the yen, changing hands at 82.52 yen from 82.42 in New York on Wednesday afternoon.
The euro bought $1.3059 and 107.79 yen, compared with $1.3064 and 107.71 yen in US trade.
Struggling Japanese electronics giant Sharp closed the morning session up 4.97 percent at 190 yen, in the wake of news it struck a capital injection deal with US-based chipmaker Qualcomm.
The cash-strapped Japanese firm's shares also benefited from Taiwan's Hon Hai Precision saying a stalled deal to invest in Sharp was still on the table.
-- Dow Jones Newswires contributed to this article --