Nikkei opened 0.14 percent higher Monday. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average added 12.31 points, or 0.14 percent, from Friday to 8,852. 22. The broader Topix index of all First Section issues on the Tokyo Stock Exchange climbed 1.21 points, or 0.17 percent, to 732. 85.