Tokyo's benchmark Nikkei index on Monday gained more than two percent on a weak yen, with investors apparently unmoved by growing speculation that the Tokyo Olympics will be postponed over virus concerns.
The Nikkei 225 index rose 2.02 percent, or 334.95 points, to close at 16,887.78, while the broader Topix index was, up 0.68 percent, or 8.79 points, at 1,292.01.
"A relatively cheap yen encouraged players to buy back shares," Shinichi Yamamoto, a broker at Okasan Securities in Tokyo, told AFP.
Heavyweight stock SoftBank Group also soared after it announced a massive sale of assets to finance share buybacks, debt repayments and an increase of its cash reserves.
The firm's shares surged 18.6 percent to 3,187 yen.
The dollar edged down 109.92 yen in Asian afternoon trade from 110.85 yen in New York but still up from 108.78 yen on Thursday in Tokyo.
Financial markets in Tokyo were closed on Friday for a national holiday.
"But today's recovery does not promise further gains," Yamamoto told AFP.
"It will be no surprise to see profit-taking tomorrow with investors cashing in on today's gain."
Investors largely ignored reports on a possible postponement of the Tokyo Olympics as the outbreak prompted athletes and sports bodies to step up pressure.
"A postponement scenario has already been factored in," Yamamoto added.
"But if the Olympics were cancelled, it would have a sizable negative impact on Japanese shares."
The Softbank announcement helped investor sentiment in Tokyo.
"The market took the surprise announcement positively at a time when it's hard to find good investment destinations," Yoshihiro Okumura, general manager at Chibagin Asset Management, told AFP.
"It's not a bad strategy to use their cash for buying back shares when the outlook of the market and the economy is very uncertain."
China-linked shares were higher, with industrial robot maker Fanuc soaring 8.48 percent to 13,165 yen, parts maker Rohm trading up 5.30 percent at 5,560 yen, and construction machinery maker Komatsu up 5.46 percent at 1,592.5 yen.
Automakers were lower, with Toyota dropping 3.48 percent to 6,172 yen and Nissan down 6.37 percent to 365.4 yen.