The yen hovered near its 2-1/2-year low against the dollar on Tuesday, bolstering Japanese shares to multi-year highs on expectations for more aggressive monetary easing from the Bank of Japan.
Other Asian stock markets were capped on earnings and US fiscal concerns. MSCI's broadest index of Asia-Pacific shares outside Japan was up 0.1%, with Australian shares up 0.2% and South Korean shares opening nearly flat.
Japan's benchmark Nikkei stock average opened up 1% to its highest level since late April 2010 on continued yen weakness, which improves earnings prospects for exporters. Japanese financial markets were closed on Monday for a public holiday.
The yen remained pressured as investors hope for bolder monetary and fiscal steps under the government of Prime Minister Shinzo Abe, whose cabinet last week approved a $117 billion stimulus package, the biggest spending boost since the global financial crisis, in an effort to support the economy.
The dollar was at 89.47 yen, near its peak since June 2010 of 89.67 yen hit on Monday, while the euro traded at 119.73 yen, near its highest since May 2011 of 120.13 hit on Monday. Against the Australian dollar, the yen hovered near 94.64, its lowest since August 2008 touched on Monday.
"The yen is likely to stay under selling pressure with 90 yen in sight, supported by expectations for the Bank of Japan to be proactive about realising a 2% inflation target," said Masafumi Yamamoto, chief FX strategist at Barclays in Tokyo.
"Improving US economic indicators have helped underpin the dollar, but the momentum seems to be slowing. Surprisingly slower US growth data could become a minor risk factor for a higher dollar/weaker yen scenario," he said.
The pan-European FTSEurofirst 300 closed at a two-week low on Monday, as a sell-off in US shares on concerns over demand for Apple's iPhone 5 prompted some profit-taking after the index hit a 22-month high earlier this month.
Investors also appear worried about potentially slowing US earnings growth. US companies reporting this week include Goldman Sachs, Bank of America, Intel and General Electric.
Analyst estimates for the quarter have fallen sharply since October. S&P 500 earnings growth is now seen up just 1.9% from a year ago, Thomson Reuters data showed.
In Seoul, Kim Young-joon, an analyst at SK Securities, noted concerns about a possible slowing in smartphone market growth.
"We are concerned that the smartphone market growth will slow down, affecting Samsung Electronics and other smartphones makers and parts suppliers," Kim said, adding that the domestic stock market's momentum has been slowing because of US debt ceiling issues.
Federal Reserve Chairman Ben Bernanke on Monday urged US lawmakers to lift the country's borrowing limit to avoid a potentially disastrous debt default, warning that the economy was still at risk from political gridlock over the deficit.
Also on Monday, US President Barack Obama refused to trade cuts in government spending in exchange for raising the borrowing limit. If the limit is not raised, the United States could default on its debt.
After narrowly avoiding the "fiscal cliff" of sharp spending cuts and tax increases just two weeks ago, Obama faces a set of deadlines by the end of February: the need to raise the debt ceiling, automatic deep spending cuts temporarily delayed in the fiscal cliff deal, and the end of a stop-gap government funding measure.
The euro was at $1.3376, slipping from an 11-month high of $1.3404 reached on Monday on fading prospects for an interest rate cut in Europe and easing anxiety over the region's debt crisis.
Data from the Bank of Spain showing net borrowing from the European Central Bank falling 2.1% in December from November also helped improve sentiment for the euro, but the euro zone remained fragile due to its weak economic environment.
US crude steadied around $94.12 a barrel.
