The yen's biggest monthly advance since 2008 is threatening profits of exporters from Toyota Motor Corp. to Nissan Motor Co., endangering the rebound from March's record earthquake.
The currency was at 77.30 per dollar at 9:34 a.m. Tuesday in Tokyo, 7 percent higher than the 82.59 average that exporters used for profit forecasts in a Bank of Japan survey released last month.
Toyota sees a yen stronger than 80 as a brake on growth and Finance Minister Yoshihiko Noda said Tuesday that the yen is overvalued.