Japanese government bond (JGB) prices ended the day mostly softer, with most market participants exercising caution ahead of January inflation data due out tomorrow, dealers said. The yield on the benchmark 10-year bond finished at 1.635, after touching a high of 1.640 pct. This is the highest close since Sept 7, 2004 when it ended at 1.645 pct. On Wednesday it finished at 1.600 pct. The yield on the lead 20-year debt rose to 2.045 pct from 2.005 pct yesterday, while the yield on the benchmark five-year bond fell to 1.090 pct from 1.100 pct previously. Bond prices move inversely to yields.