Japan’s Nikkei benchmark index rose over 2 percent Wednesday afternoon, trading at a fresh 34-year high, as the yen’s weakness against the U.S. dollar lifted sentiment and fueled buying of exporter issues. As of 1 p.m., the 225-issue Nikkei Stock Average had risen 684.43 points, or 2.03 percent, from Tuesday to 34,447.61. The broader Topix index was up 34.32 points, or 1.42 percent, at 2,447.41.