Tokyo stocks opened slightly higher Thursday on Wall Street rise overnight. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average gained 18.10 points, or 0.18 percent, from Wednesday to 9, 958.03. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was up 3.80 points, or 0.41 percent, to 932. 10. The Second Section also advanced. 