* Nikkei's 25-day moving average tops 15,000 for first time since Feb * Rakuten soars on report it is entering low-cost carries business By Ayai Tomisawa TOKYO, June 26 (Reuters) - Japan's Nikkei share average crawled back up from a one-week low on Thursday, and Rakuten Inc soared on a report it is preparing to enter the low-cost carrier business.

The Nikkei edged up 0.2 percent to 15,292.48 in mid-morning trade, helped by a better performance on Wall Street as investors focused on the U.S. Federal Reserve keeping rates low for longer after a shockingly weak U.S. first quarter GDP report.

The benchmark, which has risen around 6 percent in the past month, dropped 0.7 percent to 15,266.61 on Wednesday - the lowest closing level since June 18.

The Nikkei's 25-day moving average has just risen above 15,000 for the first time since February. The gap between the current Nikkei level and the moving average is narrowing.

"The market remains cautious about the recent rallies so it is waiting for the market to cool down a bit more," said Hikaru Sato, a senior technical analyst at Daiwa Securities.

Sato expects the Nikkei to gradually rise towards 16,000 spurred on expectations earnings for the April-June quarter will improve, and on hopes the government's growth strategy will begin to gain traction.

The recent rally in the market was driven by the Fed's commitment to keeping policy loose for an extended period, improved global data and hopes Japan's growth strategy will boost long-term growth.

E-commerce firm Rakuten surged 3.9 percent after Toyo Keizai reported on its web site that it is preparing to enter the low-cost carrier business in Japan as early as July with Malaysia's AirAsia Bhd.

However, Rakuten said in a statement that the report was not based on the company's announcement, adding it has nothing further to say on the issue at this stage.

Index heavy stocks were higher, with SoftBank Corp rising 0.7 percent and Fast Retailing Co advancing 0.3 percent.

Exporters were also attracting buyers. Panasonic Corp rose 0.7 percent and Honda Motor Co added 0.3 percent.

The broader Topix added 0.2 percent to 1,263.78, while the new JPX-Nikkei Index 400 gained 0.2 percent to 11,494.50.

(Editing by Shri Navaratnam)