TNikkei opened slightly lower Friday morning as the yen climbed against other major currencies. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average fell 48.48 points, or 0.43 percent, from Thursday to 11, 258.80. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was down 5.63 points, or 0.59 percent, at 949. 25.