The yen dropped the most in about five months against the US dollar yesterday after Japan intervened in the foreign exchange market to weaken its currency.
The yen dropped 3 per cent to 79.40 per dollar, set for the largest intraday decline since March 18 this year, when the Group of Seven nations jointly sold the currency.
Japan's 10-year bond yield fell below 1 per cent and the Nikkei 225 Stock Average rose 0.9 per cent.
Finance Minister Yoshihiko Noda said Japan took unilateral action to sell the yen, which earlier this week neared a post-war record.
The move comes a day after the Swiss central bank cut interest rates and said it would boost the supply of francs to curb the "massively overvalued" currency.