The benchmark Nikkei 225 index rose 1.34 percent, or 280.27 points, to 21,144.48, marking the highest close since December 17. The broader Topix index was up 1.06 percent, or 16.73 points, at 1,589.33.
A rise of the dollar against the yen also encouraged investors to take more risk and buy up shares.
"The market continued to surge against a background of optimism for progress in US-China trade talks, as well as receding fears about another government shutdown in the United States," said Okasan Online Securities in a commentary.
Rises of Hong Kong and Shanghai stocks helped fuel further gains in Tokyo through the afternoon session, the brokerage said.
But players refrained from making aggressive moves in the afternoon as they waited for releases of major global data, including US CPI later in the day and Japan's October-December GDP data, slated for Thursday morning.
Global investors have cheered as US President Donald Trump told reporters that he would consider extending the deadline for a trade deal with China beyond March 1.
"If we're close to a deal, where we think we can make a real deal... I could see myself letting that slide for a little while," Trump said.
The comments came as the third round of trade negotiations were set to resume in Beijing to prevent tariffs more than doubling on $200 billion in Chinese imports.
The US president, while not ruling anything out, also suggested his latest funding fight with congressional Democrats over border security would not result in another shutdown.
The dollar fetched 110.61 yen in Asian trade, against 110.48 yen in New York late Tuesday.
In Tokyo, Sony surged 2.60 percent to end at 4,980 yen, and internet investor SoftBank Group added 4.92 percent to 10,765 yen.
Honda climbed 1.73 percent to 3,001 yen, while Toyota added 0.30 percent to 6,625 yen.
Nissan shed early morning losses and ended up 0.74 percent at 938.3 yen after the automaker said it had slashed its full-year forecast.
On Wall Street, the Dow Jones Industrial Average snapped a four-day losing streak, soaring 1.5 percent to end at 25,425.76.