Nikkei opened higher Friday, rising from a nearly 3-percent tumble the previous day, as concerns over the European debt crisis eased. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 54.49 points, or 0.64 percent, from Thursday to 8,555.29, a day after the index shed 2.91 percent and ended at a five-week low. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was up 2.14 points, or 0.29 percent, to 732. 44.