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Tokyo stocks soared more than seven percent on Tuesday, boosted by a weak yen and aggressive asset-buying from the Bank of Japan and following huge support measures from the US Federal Reserve during the virus outbreak.

The benchmark Nikkei 225 index rose 7.13 percent -- the biggest jump since February 2016 -- or 1,204.57 points to close at 18,092.35, while the broader Topix index was up 3.18 percent, or 41.09 points, at 1,333.10.

The market opened sharply higher as the yen fell against the dollar as the Bank of Japan's mopped up exchange-traded funds (ETFs), dealers said.

"Market sentiment remained positive for the rest of the day," Shinichi Yamamoto, a broker at Okasan Securities in Tokyo, told AFP.

The greenback was changing hands at 110.44 yen in afternoon trade, down from 111.26 yen in New York on Monday afternoon but still sharply higher than 105-107 yen ranges seen a week ago.

A cheaper yen is good for Japanese exporters as it makes their products more competitive abroad while inflating profits when repatriated.

"But it's unlikely for only Tokyo shares to recover while others are still struggling," Yamamoto said.

"We are expecting to see ups and downs for now as a sign of an end to the outbreak has yet to be seen," Yamamoto said.

The gains in Japan were in line with a much-needed rally across Asia after the Fed unveiled a batch of aggressive measures to support the economy that essentially sees the US central bank print dollars.

In Tokyo, SoftBank Group surged 18.95 percent to 3,791 yen -- after rising more than 18 percent on Monday -- in response to news that it will sell up to $41 billion in assets to finance a stock buyback, reduce debts and increase its cash reserves after weeks of heavy losses in its shares.

Toyota gained 1.31 percent to 6,253 yen after it and major telecom group NTT jointly announced plans for a capital tie-up for a "smart city" project, putting up some 200 billion yen each.

NTT was down 2.50 percent at 2,437.5 yen.

The news came after Toyota announced temporary production suspension at five domestic plants to cope with slumping demand caused by the coronavirus outbreak.

Japan Post rose 4.79 percent to 811.3 yen on media reports that the group is planning to slash 10,000 post office personnel, five percent of its workforce.

Sony rose 5.65 percent to 6,198 yen and Canon gained 4.57 percent at 2,331 yen.