The Nikkei stock index rose Friday on hopes for solid earnings from Japanese firms after heavyweight Fast Retailing reported upbeat results and a positive outlook the previous day. The 225-issue Nikkei Stock Average ended up 224.91 points, or 0.57 percent, from Thursday at 39,605.80. The broader Topix index finished 6.47 points, or 0.24 percent, lower at 2,706.20. On the top-tier Prime Market, gainers were led by bank, retailers and insurance issues. The U.S. dollar strengthened slightly to the upper 148 yen zone in Tokyo on buying to adjust positions before the weekend, dealers said. On the s…