TOKYO, April 24 (Reuters) - Benchmark 10-year Japanese government bonds were steady on Wednesday, as the Bank of Japan announced the latest round of purchases under its new stimulus scheme. * The BOJ offered to buy 500 billion yen ($5.03 billion) in JGBs outright on Friday, with residual maturities of more than 5 years and up to 10 years, and another 500 billion yen with residual maturities of more than 1 year and up to 5 years. * "Trading activity has been thin this week, with expectations of BOJ operations supporting the market," said a fixed income fund manager at a European asset management firm in Tokyo. "The JGB market is making relatively small moves, on supply/demand factors as investors adjust their portfolios, and these conditions could continue through the Golden Week holidays," he said. * Tokyo markets will be closed for holidays on April 29, and then on May 3 and May 6. * The yield on benchmark 10-year bonds was steady at 0.585 percent, while the 10-year futures contract ended morning trade up 0.04 point at 144.71, after moving in a narrow range between 144.58 and 144.74. * The superlong sector underperformed, as the BOJ refrained from any buying in that tenor this time. The 20-year yield added 2.5 basis points to 1.470 percent, while the 30-year yield rose 2 basis points to 1.595 percent. * The BOJ will update its forecasts after its policy meeting on Friday. While no major policy steps are expected, investors will be watching for any operational tweaks to the central bank's asset-buying programme, and also whether BOJ Governor Haruhiko Kuroda's two-year time frame to hit a 2 percent inflation target will become the bank's official forecast.