Tokyo's benchmark Nikkei index rallied more than 2.7 percent on Monday as the Bank of Japan took additional easing steps to support the virus-hit economy.
The Nikkei 225 index rose 2.71 percent, or 521.22 points, to close at 19,783.22 while the broader Topix index was up 1.83 percent, or 25.96 points, at 1,447.25.
"Details of the announcement were widely anticipated but welcomed as good news," said Toshikazu Horiuchi, a broker at IwaiCosmo Securities.
The central bank said it would shift to unlimited government bond buying and more than double its capacity to purchase corporate bonds and commercial papers -- a move to back corporate financing as Japan grapples with fallout from the coronavirus.
Stocks gained ground further in afternoon trade following a rise in US stock index futures, brokers said.
"And news about plans to resume business activities overseas is also encouraging investors," Horiuchi told AFP.
The dollar was trading at 107.26 yen in Asian afternoon trade, against 107.46 yen in New York late Friday.
"Japanese stocks this week will move one step forward and one step back, ahead of a set of holidays," Okasan Online Securities said in a commentary.
In Tokyo, some high-tech shares were higher, with industrial robot maker Fanuc surging 11.94 percent to 16,630 yen and chip-testing equipment manufacturer Advantest rallying 8.36 percent to 5,180 yen, after they both reported better-than-expected fourth-quarter operating profits.
Market heavyweight SoftBank Group jumped 4.48 percent to 4,592 yen and Uniqlo operator Fast Retailing gained 2.94 percent to 48,980 yen.
Sony was up 1.08 percent at 6,779 yen and Toyota rose 1.77 percent to 6,659 yen.
After the closing bell, Panasonic announced it had revised down sales forecasts for the fiscal year through March due to the impact of the virus pandemic.
Its full-year sales are projected to reach 7.45 trillion yen, down from an earlier forecast of 7.70 trillion yen.
The firm expects net profit to stand at 210 billion yen, up from 200 billion yen, citing improvement in income taxes, while operating profit forecasts remain unchanged.