TOKYO, Oct 14 (Reuters) - Japan's Nikkei share average

sank on Tuesday after reopening from a long weekend, pressured

by uncertainty surrounding the country's next premier and

persistent U.S.-China trade tensions.

The Nikkei ended the morning session down 1.2% at

47,520.57, with just 31 of its 225 components rising, 192

declining and two trading flat.

The broader Topix slid 1.4% to 3,153.50.

Japanese investors returning from a national holiday on

Monday faced a complex global backdrop, including a stronger yen

and Wall Street sell-off on Friday. While both saw partial

reversals, market sentiment remained fragile as shifting signals

from U.S. President Donald Trump continued to unsettle traders.

On balance, weaker U.S. stocks and a stronger yen since the

start of Japan's extended weekend weighed on the market, said

Maki Sawada, an equity strategist at Nomura Securities.

In addition, the initial euphoria from fiscal dove Sanae

Takaichi's election as leader of the Liberal Democratic Party at

the start of the month has faded after coalition partner Komeito

pulled support. This opened a small possibility of an opposition

party leader being elected prime minister by parliament later

this month. Local media say October 20 or 21 are likely dates

for the vote.

"The decline of the 'Takaichi trade' is one reason" for

weakness in Japanese stocks on Tuesday, Sawada said. "Political

uncertainty is weighing."

Exporters, whose overseas revenue is crimped by a stronger

currency, dropped on Tuesday, with Toyota ( TM ) down 1.1%.

Tyremakers also experienced outsized declines, making the rubber

sector the worst performer among the Tokyo Stock

Exchange's 33 industry groups.

SoftBank Group slumped 3.8%, extending its pullback

from a record high on Thursday as the heavyweight startup

investor continued to retreat.

Still, many chip-sector shares advanced, tracking upbeat

performances among Wall Street peers overnight. Lasertec ( LSRCF )

rose 3% and Sumco ( SUMCF ) gained 2.5%.

"Expectations for growth in artificial intelligence remain

in place," said Nomura's Sawada.

Elsewhere, Muji owner Ryohin Keikaku ( RYKKF ) surged 12.3%

following its earnings announcement after the closing bell on

Friday, making it the Nikkei's top performing stock.