Tokyo stocks opened slightly lower on Friday morning as investors locked in gains after the previous day' s surge. At 9:15 a.m., the 225-issue Nikkei Stock Average was down 57.28 points, or 0.40 percent, from Thursday at 14,427.85. The broader Topix index of all First Section issues on the Tokyo Stock Exchange lost 2.46 points, or 0.21 percent, to 1,179. 74. Decliners were led by mining, utility and nonferrous metal shares while real estate, paper and shipping issues gained ground.