LOS ANGELES Japanese stocks saw their opening gains vanish in early Friday trading, with the Nikkei Stock Average down 0.2% at 9,385.92 after rising 1% the previous day, and the Topix also off 0.2%. A slightly stronger yen helped limit gains, while a better-than-expected result for October industrial production offered little help. Many blue-chip electronics and industrial names saw losses, with TDK Corp. down 1.3%, Pioneer Corp. 2.6% lower, and Renesas Electronics Corp. dropping 2%. On the upside, Hitachi Ltd. rose 2.4%, and Mitsubishi Heavy Industries Ltd. gained 1.9%, after the two companies announced a deal to merge their thermal-power equipment businesses. Also rallying, oil major JX Holdings Inc. surged 3.7% after its refining unit said late Thursday that it plans to raise its December crude throughput by 14% compared to a year earlier.