The yen hit its lowest level in nearly four years against the dollar in Asian trade on Monday as the Bank of Japan's sweeping monetary easing last week continued to affect the markets.
The dollar was at 98.35 yen in Tokyo midday trade, up from 97.54 yen in New York Friday afternoon, hitting its highest level since June 2009 and boosting Japanese exporter shares.
"The big FX mover was the continuing decline in the Japanese yen" in the wake of ramped up monetary easing by the Bank of Japan (BoJ), National Australia Bank said in a note.
The euro also rose to 127.79 yen from 126.70 yen in US trade while buying $1.2994 against $1.2990 trade.
The euro-yen is likely to trade in a 127.00-129.00 range Monday, said a senior dealer at a major bank in Tokyo, noting investors would likely take cues from the dollar-yen moves.
"But market volatilities have just been too high, and I'm getting irritated at that," he told Dow Jones Newswires.
BoJ governor Haruhiko Kuroda surprised markets Thursday by announcing bolder-than-expected easing steps.
Kuroda said the bank would boost money supply massively and jack up asset purchases to hit a two-percent inflation target, vowing no let-up in the battle against falling prices which have plagued the economy for decades.
Capital Economics said a further significant fall in the yen probably lay ahead.
While the economic research firm still assumes that the yen will receive a safe-haven-related boost from a re-escalation of the eurozone crisis later this year, it believes this will prove short lived.
It predicts the dollar-yen rate at 105 at the end of 2013 and 120 at end-2014.