Tokyo's Nikkei stock index soared to a fresh six-year high Thursday after the US Federal Reserve said it would start scaling back its bond-buying programme from next month. The benchmark Nikkei was up 1.74 percent, or 271.42 points, to 15,859.22, its best finish since December 2007. The Topix index of all first-section shares added 1.01 percent, or 12.58 points, to 1,263.07.