Tokyo stocks opened 0.70 percent higher on Monday after the yen continued to fall against other major currencies.
The Nikkei 225 index at the Tokyo Stock Exchange was up 76.21 points at 11,002.86 at the start.
"The weaker yen continues to fuel the ongoing rally," said SMBC Nikko Securities general manager of equities Hiroichi Nishi.
"And with earnings reporting season kicking into high gear this week, companies' outlooks for the (January-March) fourth quarter will be closely watched," he told Dow Jones Newswires.
The dollar was at 91.09 yen in early Asian trade, up from 90.87 yen in New York Friday afternoon.
The euro rose to $1.3466 and 122.54 yen from $1.3457 and 122.28 yen in US trade.
Bullish Wall Street activity was also encouraging, with the much-watched S&P 500 closing above the 1,500 mark for the first time in five years on Friday.
The broad-based S&P 500 added 0.54 percent to 1,502.96 as strong earnings reports from Procter and Gamble, Halliburton and other equities propelled US markets higher.
The Dow Jones Industrial Average closed up 0.51 percent to 13,895.98, its best level since October 2007.
