The yen soared to as high as 135-to-the-dollar in Tokyo trading Thursday after Japanese and U.S. authorities surprised overseas currency markets with joint intervention overnight.
The yen's unexpected rise, a 9 percent leap from late Monday, also had an immediate effect on Japanese share prices and in overseas currency and stock markets.
At 5 p.m. in Tokyo, the dollar was changing hands at 136.87-90 yen, down more than 5 yen from 141.98-142.01 yen the same time Wednesday. At one point in morning trading, the dollar went as low as 135.50 yen, its lowest level in Tokyo since May 22 and nearly 11 yen down from late Monday's 146.43-46 yen.
The bullish tone, inherited from trading Wednesday in New York and London, where the intervention took place, boosted the Nikkei average 646.16 points to 15,361.54.
For the U.S., it was the first intervention in foreign-exchange markets since 1995 and its first yen-buying operation in more than six years. The joint action pushed the dollar down 6.90 yen from late Tuesday's levels in New York to 136.45-55 yen, as of 5 p.m. Wednesday.
The yen's tide lifted the rest of Asia as well. In South Korea, the key index climbed 7.1 percent and closed at 325.49 points. The key Weighted Price Index in Taiwan shot up 4 percent to hit 7,768.31 points.
In New Zealand the key NZSE-40 capital index ended 1.6 percent up at 2,031.96 points. The Australian All Ordinaries Share Index also rose, climbing 2.3 percent to close at 2,031.96 points.
In early trading, the Stock Exchange of Thailand index skyrocketed 10.7 percent.
In Indonesia meanwhile, the key JSX Composite Index closed its morning trading session up 3.7 percent, at 435.010 points. The Malaysian Composite Index was even higher, improving 7 percent to reach 482.61 points at midday.
Hong Kong's blue-chip Hang Seng Index was 7.8 percent higher, hitting 8,627.51 points at midday.