Japan's Nikkei soared 5.7%, on track for its biggest rise in one day since March 2011, after Prime Minister Shinzo Abe reiterated a pledge to lower the corporate tax rate. In the previous session, the Nikkei lost 2.4% and wiped out its year-to-date gain.
Asian shares caught a tailwind on Wednesday on the heels strong rallies in the United States and Europe, with Japanese stocks on course for their biggest one-day gain in 4 1/2 years.
Japan's Nikkei soared 5.7%, on track for its biggest rise in one day since March 2011, after Prime Minister Shinzo Abe reiterated a pledge to lower the corporate tax rate.
In the previous session, the Nikkei lost 2.4% and wiped out its year-to-date gain.
The MSCI's broadest index of Asia-Pacific shares outside Japan also rallied hard, rising 2.5% as of 0326 GMT, with gains across all the major indices that were open.
Major Wall Street indices all posted gains of more than 2% overnight.
European stocks also had a banner day on news Germany's imports and exports hit record highs in value terms in July.
Chinese shares rose late on Tuesday after negotiating some dour economic news in the form of a bigger-than-expected drop in imports. The trade data raised fears that China's slowdown could be sharper than many had expected, which in turn raised hopes that Beijing would muster more easing steps to prevent a hard landing.
The Shanghai Composite index climbed 1.6% on Wednesday. Hong Kong's Hang Seng index added 2.9%.
"With many markets having been sold off heavily over recent weeks, today's rally, like the US last night, represents a speculative bounce," said Angus Gluskie, managing director of White Funds Management in Sydney.
"The market will remain susceptible to a return of negativity until we see signs of some improvement in the original causes of weakness, which were predominantly Chinese growth concerns," he said.
The dollar put in a mixed performance, rising slightly against a basket of six rival currencies to 96.054, and slipping 0.2% against the euro to $1.1177.
The greenback also firmed about 0.5% against the yen to 120.33 as the improved market mood tempered the appeal of the safe-haven Japanese currency.
The euro also gained on the yen, rising 0.2% to 134.49.
Crude oil futures remained steady but at low levels on lingering concerns about a global supply glut.
US crude rose 0.2% to $46.15 ahead of weekly crude inventories data due from industry group American Petroleum Institute later in the session.
Brent crude added 0.5% to $49.76, after jumping 4% the previous session following upbeat German economic data.
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