The Japanese yen has dropped to its lowest level since 2008 against the US dollar after the Bank of Japan began the latest round of a stimulus programme.
The yen fell as low as 98.85 against the dollar, before rebounding slightly.
Investors said the bank's plan to buy assets worth trillions of yen, which has government backing, would continue to weaken the currency.
As a result, the BBC reports the yen may break through the 100 mark against the dollar later this week.
Last week, the Bank of Japan said it would double the supply of the currency in the market. It added that it would be much more aggressive in pursuing a 2% inflation target to boost growth.