Nikkei opened slightly lower early Friday morning due to selling to lock in recent sharp gains after it advanced for four sessions in a row. At 9:15 a.m., the 225-issue Nikkei Stock Average lost 64.38 points, or 0.46 percent, from Thursday at 14,000.44. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 3.69 points, or 0.32 percent, at 1, 154.15.