Tokyo shares ended the morning session 1.05 percent higher on Thursday after touching their highest level in six months at one point thanks to the weak yen.
The benchmark Nikkei 225 index at the Tokyo Stock Exchange was up 96.84 points at 9,319.36 by the break while the broader Topix index of all first-section shares rose 0.90 percent, or 6.87 points, to 773.88.
The Nikkei had earlier surged above 9,350 to its strongest level since May, though volume was light ahead of the US Thanksgiving holiday and a public holiday in Japan on Friday.
Speculation of further easing by the Bank of Japan has weighed on the yen, which has been cheered by investors as it makes the nation's exporters more competitive overseas.
Expectations the central bank will again loosen monetary policy has been fuelled further by data showing the worst October trade figures in more than 30 years.
That came after opposition leader Shinzo Abe said last week that he would pressure the central bank for aggressive easing measures if his party wins, as expected, next month's general election.
However, some have cast doubt on Abe's ability to force the BoJ to fall in line with his plan, with John Higgins at Capital Economics saying in a note: "We don't expect a major shift in the BoJ's stance."
He added that "we still think that demand for a safe haven from the crisis in the eurozone will instead keep the yen firm for the next year or two".
Sentiment on Thursday was also boosted after banking giant HSBC said China's November manufacturing activity grew for the first time in more than a year, while investors eyed efforts to seal a bailout package for debt-hit Greece.
In Asian currency markets, the euro fetched $1.2844, up from $1.2826 in New York late Wednesday, while it bought 105.90 yen against 105.84 yen.
The dollar retreated from gains in early Asian trade to buy 82.47 yen against 82.51 yen.