TOKYO, April 2 (Reuters) - Japan's Nikkei share average oscillated between gains and losses on Wednesday as traders nervously awaited U.S. President Donald Trump's latest round of tariffs.

The Nikkei at one point slipped 0.56% to 35,426.33, its lowest since September 11, 2024, after opening 0.36% higher at the session's high of 35,751.02. It traded flat at 35,630.18 as of 0153 GMT.

The broader Topix also opened higher but quickly reversed direction to sink as much as 1.17%. It was last down 0.59%.

Energy shares were under particular pressure on the Tokyo bourse after crude oil eased off five-week highs overnight. The electric and gas sub-index dropped 2.25% and the mining sub-index, which includes oil explorers, declined 2%.

The Nikkei performed relatively better due to gains for some of its most heavily-weighted stocks, including Uniqlo-owner Fast Retailing ( FRCOF ) and chip-making equipment major Tokyo Electron ( TOELF ), which rose about 2.7% each.

For weeks, Trump has trumpeted April 2 as "Liberation Day," which will see dramatic new duties that could upend the global trade system. A White House Rose Garden announcement is scheduled for 2000 GMT, which will be very early on Thursday morning in Japan.

The White House said on Tuesday that reciprocal tariffs will take effect immediately after Trump announces them, but provided no details about the size and scope of the trade barriers.

The 25% tariff on auto imports will take effect on April 3.

"It's very difficult to read what will happen, that's the situation we're in," said Kazuo Kamitani, an equities strategist at Nomura Securities.

"We need to pay close attention to the news flow out of the U.S., and if the news flow is bad, the Nikkei could drop as much as 600 yen" to around the 35,000 level, which should provide a near-term floor, Kamitani said. (Reporting by Kevin Buckland; Editing by Sumana Nandy)