TOKYO, Oct 12 (Reuters) - Japanese stocks ended flat after a bumpy trading session on Wednesday, with sliding tech companies countering gains in travel-related firms in a market that lacked direction ahead of this week's key U.S. inflation data.

The Nikkei share average opened down 0.18% and swung between losses and gains throughout the day, before closing down 0.02% at 26,396.83. The broader Topix lost 0.12%.

The biggest loser on the Nikkei was semiconductor equipment maker Tokyo Electron Ltd, which fell 4.39% amid ongoing struggles in the chips industry. The Philadelphia semiconductor index has declined for four straight sessions.

"It doesn't look like growth stocks, in particular semi-conductor-related stocks, have bottomed out," said Hiroyasu Mori of Okachi Securities, who pointed to reports of Apple's suspension of an iPhone production increase as a spark for the trend.

"For now, it seems the market will be selling off high-tech stocks and buying stocks related to domestic demand," he said.

Demand was strong for system-on-chip designer Socionext Inc , however, which started trading on Wednesday after what is said to be the biggest IPO in Japan so far this year.

Shares in Socionext closed at 4,200 yen, 15.07% higher than the initial offer price.

The yen plunged to new 24-year lows, falling as far as 146.39 to the dollar. The Japanese currency hadn't fallen below 146 since 1998, and the Ministry of Finance intervened to prop it up in September when it reached 145.9.

A weaker yen can help some Japanese exporters, who benefit from cheaper foreign sales. Topix transportation equipment stocks were up 1.06%, though that included several automakers like Mitsubishi Motor, which fell 3.91%.

Overall, the market lacked direction as it awaited the Consumer Price Index (CPI) report on Thursday, which will be scoured for clues to inflation and rate hikes that could follow to tame it.

"The CPI has often caused turbulence until now, so a lot of investors want to wait and see what happens," said a strategist at a domestic securities firm.

The best performers on the Nikkei were related to travel and retail, as Japan opens its borders for regular tourism this week.

Central Japan Railway Co and West Japan Railway Co both gained more than 2%, while 7-11 owner Seven & I Holdings Co Ltd and department store operator Aeon Co Ltd jumped by more than 3% each.

Of the Nikkei's 225 constituents, 143 declined, 75 advanced, and seven traded flat. (Reporting by Sam Byford and Tokyo markets team; Editing by Subhranshu Sahu)