TOKYO, Aug 12 (Reuters) - Japan's benchmark stock index jumped to a seven-month high on Friday, with SoftBank Group and other tech heavyweights leading the charge, as signs of cooling U.S. inflation raised hopes for smaller Federal Reserve rate hikes and boosted risk appetite.

The Nikkei share average rose as much as 2.5% to 28,507.31, its highest since Jan. 18, before ending the morning session 2.37% higher at 28,479.99. It has risen 1.08% so far this week in what would be its second straight weekly gain.

The broader Topix had gained 1.83% to 1,969.02 by the midday break and was on course to rise 1.12% for the week.

Japanese markets were closed on Thursday for a local holiday.

Data released on Wednesday showed that U.S. consumer prices were unchanged in July compared with June, prompting bets that the Fed could slow down its rate hikes.

"The Japanese market is stronger today than I had expected," said Jun Morita, general manager of the research department at Chibagin Asset Management. "One reason for not buying stocks has been eliminated after investors confirmed the slower pace of U.S. inflation."

SoftBank Group jumped 6.85% and was the biggest boost for the Nikkei after the technology investor said it would book a $34.1 billion gain by trimming its stake in Alibaba Group Holding.

Chip-making equipment maker Tokyo Electron advanced 4.75% and robot maker Fanuc climbed 5%.

Honda Motor rose 3.15% after the automaker raised its outlook for full-year operating profit thanks to a weaker yen.

All but one of the Tokyo Stock Exchange's 33 industry sub-indexes rose, with electric machinery makers leading the rally with a 2.74% gain.

(Reporting by Junko Fujita; Editing by Subhranshu Sahu)