(Rewrites paragraph 1, adds comments, updates stock prices)

By Junko Fujita and Rocky Swift

TOKYO, Nov 25 (Reuters) - Japan's Nikkei stock gauge

erased most of its early gains to end nearly flat on Tuesday as

SoftBank Group tanked almost 10% on concerns about competition

between OpenAI's ChatGPT and Google's Gemini.

The Nikkei 225 Index was up 0.07% at 48,659.52,

after rising as much as 1.14%. The broader Topix was

down 0.21% at 3,290.89.

"Investors were concerned about the competitiveness of

ChatGPT from OpenAI, in which SoftBank Group invests, with

Google's new Gemini," said Kazuaki Shimada, chief strategist at

IwaiCosmo Securities.

Alphabet's launched the latest version of its

artificial intelligence model Gemini last week, sending its

shares to a record high.

"Typically, Japan's AI-related heavyweights move in the same

direction, but today SoftBank Group fell on its own reason,"

said Shimada.

SoftBank Group ended 9.95% lower, shaving 338

points off the Nikkei, which rose by 33.64 points.

Chip-related Advantest ( ADTTF ) and Tokyo Electron ( TOELF )

rose 4.18% and 3.05%, respectively, mirroring strong

performances among technology shares on Wall Street.

Major share indexes on Wall Street closed higher on Monday

for a second session, as bets solidified that the U.S. Federal

Reserve will deliver another interest rate cut in December. The

tech-heavy Nasdaq spearheaded the rally, driven by strong

performances from artificial intelligence-related stocks.

The Japanese market was closed on Monday for a public

holiday.

On Tuesday, there were 122 advancers in the Nikkei against

99 decliners.

The sharpest advancers were Eisai ( ESALF ), which rose 7.4%.

The drugmaker, a co-developer of Alzheimer's treatment Lequembi,

rose after Novo Nordisk said clinical trials of its

semaglutide drug failed to help slow the progression of the

brain-wasting illness.

Tokyo Electric Power ( TKECF ) fell 6.41% after a regional

governor approved a partial restart of its Kashiwazaki-Kariwa

nuclear power plant, which would be the first restart of a

facility for TEPCO ( TKECF ) since the March 2011 tsunami destroyed its

Fukushima Daiichi power plant.