The dollar and the euro stayed within a tight range in subdued holiday trade Monday as players searched for fresh incentives.
The dollar barely moved at 77.99 yen, little changed from 78.06 yen in New York Friday.
The euro was at $1.3059 and 101.88 yen, also little changed from $1.3040 and 101.86 yen in New York Friday.
"The market here will barely move due to the absence of fresh leads," a senior dealer at a Japanese bank told Dow Jones Newswires.
Many operators left the market, with major markets including London and New York closed for Christmas holidays.
The forex market barely reacted to the approval Friday by the US Congress of an extension of a popular payroll-tax cut, the Tokyo dealer said.
Any gain by the euro will be weighed by lingering worries over the eurozone debt crisis, he said.
The dollar was flat to firm against other Asian units.
It bought Sg$1.2914, compared with Sg$1.2912 in Friday trade in Singapore, when Japanese players took a break for a national holiday. It stood at Tw$30.28 compared with Tw$30.29 Friday.
It edged up to 43.53 Philippine pesos from 43.47, to 1,153.40 South Korean won from 1,149.15, to 31.34 Thai baht from 31.29 and to 9,050.00 Indonesian rupiah from 9,015.00.