By Agence France-Presse
The Nikkei 225 index rose 0.92 percent, or 207.33 points, to 22,760.55 in early trade. The broader Topix index was up 0.76 percent, or 13.56 points, at 1,807.03.
"Investors are welcoming progress in the US tax cut talks," said Toshikazu Horiuchi, a broker at IwaiCosmo Securities.
Wall Street stocks pushed to fresh records Friday as key congressional holdouts on a US tax cut proposal signalled their support, pushing the long-awaited measure closer to the finish line.
All three major US indices finished at records, with the Dow Jones Industrial Average rising 0.6 percent as Republican leaders appeared poised at last to hand President Donald Trump a major win.
"Investors are also buying on dips following four days of decline," Horiuchi told AFP.
Rakuten rose 0.39 percent to 1,029 yen after the online commerce giant faced heavy selling last week on its investment plan to set up its own mobile carrier in Japan.
Obayashi fell 0.29 percent to 1,372 yen following reports investigators plan to raid it and three other major contractors over a bid-rigging scandal on the nation's Maglev train project.
Exporters were generally higher as Toyota rose 1.24 percent to 7,053 yen with Panasonic up 0.89 percent at 1,683.5 yen.
The dollar traded at 112.68 yen, compared with 112.63 yen in New York late Friday.