Japanese stocks dropped 1.6 per cent Tuesday as investor sentiment was hurt by a stronger yen and persistent concerns about European debt problems. The benchmark Nikkei 225 Stock Average lost 142.92 points, or 1.61 per cent, to 8721.24 while the broader-based Topix index was down 13.09 points, or 1.70 per cent, at 755.04, according to a report of the German Press Agency \"DPA\"