* Financial stocks, exporters gain ground
* Kobe Steel gains after automakers declare some products safe
TOKYO, Oct 19 (Reuters) - Japan's Nikkei share average rose for the 13th straight session on Thursday, establishing its longest winning streak since 1988 while scaling a fresh 21-year peak as gains in global stocks and a weaker yen cheered investors.
The Nikkei ended up 0.4 percent at 21,448.52, after rising as high as 21,503.85, its loftiest level since 1996.
"These levels are scary," said Ayako Sera, senior market economist at Sumitomo Mitsui Trust.
"Everything must end sometime. There are no strong incentives to sell Japanese stocks at the moment, but there aren't strong incentives to buy them, either, particularly with growth in China slowing," she said.
Data released on Thursday showed China's economic growth slowed slightly as expected in the third quarter as the government's efforts to rein in the property market and debt risks tempered activity in the world's second-largest economy.
While Japanese Prime Minister Shinzo Abe's ruling bloc is expected to secure a roughly two-thirds majority in Sunday's general election, a surprisingly poor showing could provide investors with an excuse to sell stocks, Sera said.
Buoyant U.S. shares helped lift their Japanese counterparts. On Wednesday, the Dow Jones Industrial Average closed above 23,000 for the first time.
A slightly weaker yen also underpinned exporters' shares. The dollar traded above the 113 yen level for the first time in two weeks.
Shares of Kobe Steel gained 6.7 percent, after three Japanese automakers on Thursday confirmed the safety of aluminium components made by Japan's No. 3 steelmaker, which earlier this month admitted to falsifying quality data.
Financial stocks also gained ground, with insurers Dai-ichi Life Holdings advancing 1.4 percent, T&D Holdings by 1.6 percent and Mitsubishi UFJ Financial Group by 1.1 percent.
CME Group and Japan Exchange Group, the operator of the Tokyo Stock Exchange, announced the launch of yen-denominated Topix futures contracts to begin trading on CME Globex in April 2018.
The broader Topix gained 0.3 percent to 1,730.04. (Editing by Richard Borsuk)