The yen neared a historic low against the euro and also slipped against the US dollar on Friday after weak Japanese consumer inflation data, traders said.
The dollar held stable against Europe's common currency after a speech by Federal Reserve chief Ben Bernanke failed to provide any clues about the direction of US interest rates.
Around 9pm GMT, the euro was little changed at US$1.2752 from US$1.2758 late in New York on Thursday.
The euro jumped to ?149.55 from ?148.68 late on Thursday. The currency has never breached the ?150 level against the yen in its seven-year history.
The dollar rose to ?117.26, from ?116.55 on Thursday.
Japan said on Friday its core consumer prices rose by just 0.2 percent in July and revised down figures for previous months, raising doubts about prospects of another interest rate hike this year.
Analysts said the subdued figure, which was largely due to changes to the way the consumer price index is calculated, did not mean Japan's recovery was coming unstuck but could make it hard for its central bank to move again soon.
"I now personally think that there will be no additional rate hike in Japan before the end of this year," BNP Paribas currency trader Koichi Yoshikawa said.
"As there is emerging risk that the recent slowdown in the IT [information-technology] industry may spill over to other sectors in Japan, the Bank of Japan may not be in a hurry," he said.
Japanese interest rates now stand at 0.25 percent after the Bank of Japan last month raised borrowing costs for the first time in almost six years.
Asia's largest economy had been trapped in a deflationary spiral for almost eight years, but is now on course to its longest post-war recovery.
There was little else direction for the dollar after Bernanke, addressing the Fed's annual retreat in Jackson Hole, Wyoming, discussed threats to world economic integration but made no reference to monetary policy.
Bernanke said that international terrorism was a menace to globalization and could hamper further integration of the world economy.
Traders are eager for signals on the likelihood of further interest rate rises by the US central bank, which earlier this month paused in its tightening campaign after 17 straight hikes.
The greenback has largely shrugged off recent data that show the US economy flagging. It has been helped by capital inflows as risk-averse investors pull funds out of emerging markets, dealers said.
Sterling was little changed following confirmation that Britain's economy grew at a two-year high during the second quarter, compared with the first three months of this year.
At 9pm GMT on Friday the pound bought US$1.8871, compared with US$1.8862 late Thursday.
The Taiwan dollar fell 0.68 percent in the week to close at NT$32.888 against the US dollar, from NT$32.667 a week earlier.
On Friday, the Australian dollar closed at US$0.7582, down slightly on the previous week's US$0.7606.
The New Zealand dollar ended the week at US$0.6351, down from US$0.6404 the previous Friday.
The yuan closed at 7.9763 to the US dollar on Friday, compared with 7.9725 yuan on the previous day and 7.9745 a week before, traders said.
The US-dollar pegged Hong Kong dollar closed the week nearly flat at HK$7.776, from the previous week's close of HK$7.777.
The greenback was at S$1.5778 on Friday from S$1.5742 the previous week.