Tokyo stocks jumped 2.99 percent Wednesday with the yen weakening as the Bank of Japan started a two-day policy meeting, and after Wall Street pushed to a record high.
The benchmark Nikkei 225 index added 358.77 points to 12,362.20 by the close, while the Topix index of all first-section shares climbed 1.93 percent, or 19.09 points, to 1,010.43.
TEPCO soared 24.20 percent to 313 yen as investors bet on the volatile stock amid speculation that Tokyo is considering ways to limit the embattled firm's liability over the 2011 crisis at its crippled Fukushima atomic plant.
An equity strategist at a foreign brokerage said the buying was purely speculative, partly driven by Japan's cabinet on Tuesday approving a plan to open up the nation's power industry to more competition.
The utility -- one of the world's largest -- is facing billions of dollars in compensation and clean-up costs over the accident two years ago.
"There is speculation that with the industry reforms being adopted talk may also spread to somehow help TEPCO to escape some of the more severe penalties imposed on it by the prior (government)," the strategist said.
Japan's Kyodo news agency reported that TEPCO could save 175 billion yen ($1.9 billion) in annual fuel costs if a planned thermal plant uses coal rather than oil.
US stocks reached new levels Tuesday on solid manufacturing orders data and strong results from US automakers. The Dow Jones Industrial Average closed at an all-time high of 14,662.01, up 0.61 percent.
That helped ease concerns among global investors over a potential fall on Wall Street after US stocks had appeared to struggle to find upward momentum in recent days, said Kenichi Hirano, market analyst at Tachibana Securities.
"Everyone was worried about falls in New York stocks," he told Dow Jones Newswires. "It's all OK now."
Market participants are now focusing on the outcome of a two-day policy meeting of the Bank of Japan (BoJ) which started Wednesday and a European Central Bank meeting on Thursday, as well as US jobs data on Friday, he said.
The BoJ meeting is the first under a new management team at the central bank, who have pledged aggressive easing measures to beat Japan's stubborn deflation and stoke growth in the limp economy.
In Tokyo stock trading, Sony was up 0.70 percent to 1,570 yen, Toyota jumped 3.79 percent to 4,790 yen, Canon climbed 0.77 percent to 3,270 yen, All Nippon Airways added 1.08 percent to 187 yen and brokerage giant Nomura was 0.71 percent higher to close at 560 yen.
In afternoon Tokyo currency trading, the dollar strengthened to 93.54 yen against 93.39 yen in New York late Tuesday.
The euro was slightly weaker at 119.65 yen from 119.70 yen following the release Tuesday of poor manufacturing and jobs data for the 17-nation eurozone.