The Nikkei 225 Index decreased 277 points or 0.42 percent on Monday to close at 66129 points. The decline was led by Toho Zinc (-7.28%), Mitsubishi Materials (-6.92%) and Japan Steel Works (-5.41%). On the upside, the strongest performers were Tokai Carbon (7.97%), Kansai Electric Power (7.31%) and Casio Computer (5.28%).