The Nikkei share average slid 0.31% to 28,770.26 by 0215 GMT, while the broader Topix inched down 0.16% to 1,919.86.

"Investors want to confirm the strength of U.S. recovery from the factory and job data to be announced later," said Masahiro Ichikawa, chief market strategist at Sumitomo Mitsui DS Asset Management.

U.S. factory activity numbers will be released on Tuesday, while payrolls data, to be out on Friday, will be the main event of the week. Median jobs forecasts are pegged at 650,000, but the outcome is uncertain following April's unexpectedly weak 266,000 gain.

Among shares and sectors in Japan, steel makers led the Nikkei's declines, with JFE Holdings falling 2.81% and Nippon Steel losing 2.38%.

IHI jumped 3.61% after Nomura Securities changed its rating for the heavy-industry manufacturer, while its peer Mitsubishi Heavy Industries gained 2.29% after Nomura raised its target price.

Renesas Electronics rose 2.6% after the chipmaker said it expects a domestic chip plant that had been damaged in a fire in March to return to full production capacity around mid-June.

Toyota Motor Corp, up 1.72%, gained the most among the top 30 core Topix names, followed by Murata Manufacturing , which gained 1.22%.

The underperformers among the Topix 30 were Takeda Pharmaceutical Co Ltd, falling 1.72%, followed by Recruit Holdings losing 1.66%.

There were 96 advancers on the Nikkei index against 121 decliners.

(Reporting by Junko Fujita; editing by Uttaresh.V)