The benchmark Nikkei 225 index at the Tokyo Stock Exchange gained 121.06 points to 9,046.10 by the break, topping the 9,000 mark for the first time since July 6.

The broader Topix index of all first-section issues rose 1.04 percent, or 7.74 points, to 755.06.

Trading was thin due to the traditional summer holiday season in Japan.

US inflation and industrial production data Wednesday pointed to continued improvement for the world's biggest economy, while exporters got a boost from the weaker yen.

"A weakening yen is supporting the (Nikkei) index," Marusan Securities head of investment information Takashi Ushio told Dow Jones Newswires.

"(But) with the index hitting the psychologically important 9,000 level, any further gains may be limited, given few market participants and amid a lack of trading cues."

A stock dealer at a major Japanese brokerage said: "Investors are unwinding their short positions on oversold stocks such as electronics companies and steelmakers."

Sony rose 3.25 percent to 920 yen while Nippon Steel gained 2.45 percent to 167 yen.

Shares in Sharp, which dived to a fresh multi-decade low Wednesday, turned up 3.55 percent to 175 yen after news reports that it was in talks with an overseas firm over the sale of a solar battery plant in western Japan.

Japan Tobacco was up 4.79 percent at 2,556 yen after Wednesday's 4.83 percent fall on an Australian court ruling that upheld new tobacco plain-packaging laws.

On currency markets, the dollar firmed to 79.16 yen from 78.87 yen in New York late Wednesday, reaching its highest level in a month.

The euro fetched $1.2292 and 97.30 yen against $1.2285 and 96.91 yen in US trade.