Tokyo stocks opened slightly higher Friday after two days of losses. In the first 15 minutes of trading, the benchmark Nikkei-225 index gained 15.51 points, or 0.15 percent, from Thursday to 10, 230.15. The broader Topix index of all First Section issues on the Tokyo Stock Exchange rose 0.22 points, or 0.02 percent, to 942.99. The Second Section lost ground. 