Tokyo stocks opened 0.23 percent higher on Wednesday after the dollar rose past the 100 yen mark for the first time in about a month.
The benchmark Nikkei 225 index was up 32.13 yen at 14,130.87 in the first few minutes of trading.
"After four straight days of gains, the market is showing signs of becoming technically overheated, but the dollar's continuing ascent will trump those worries, at least in the early part of trading," said SMBC Nikko Securities general manager of equities Hiroichi Nishi.
The Nikkei gained nearly 10 percent in the four-day rising streak to Tuesday.
The dollar Tuesday strengthened against other major currencies as solid US economic data bolstered the chance the Federal Reserve will taper its bond-buying programme.
The greenback was changing hands at 100.81 yen in early Asian trade Wednesday against 100.63 yen late Tuesday in New York, where the dollar rose past the 100 yen mark for the first time since early June.
The euro bought $1.2974 and 130.79 yen against $1.2978 and 130.60 yen.
US stocks Tuesday reversed early gains and ended lower on revived concerns about the eurozone and the political crisis in Egypt. The Dow Jones Industrial Average dropped 42.55, or 0.28 percent, to 14,932.41.
US markets will be on reduced trading hours Wednesday before the July 4 Independence Day holiday, which may have the effect of reducing Tokyo participation levels, traders said.
-- Dow Jones Newswires contributed to this article --