A report showing U.S. retailers posted their biggest monthly decline in more than three years last month pushed the dollar to a session low at 100.88 yen, down more than 1 percent from late Tuesday.
The euro also gave up ground against the yen and dollar as global stock markets weakened.
The dollar was last trading at 101.10 yen, down 1.1 percent and close to a session trough of 100.88 yen. The euro was down 1.4 percent at 137.37 yen and down 0.2 percent at $1.3587. Sterling rose 0.8 percent to $1.7549.
The low-yield Japanese currency rallies when risk appetite wanes as investors rush to get out of trades in higher-yielding currencies and assets financed with cheaply borrowed yen.
Canada's currency weakened for a second day as crude oil fell below $75 a barrel and reports showed the U.S. economy may fall into recession.
The Canadian dollar has fallen 13.4 percent since July 11 when crude reached a record $147.27. Canada relies on commodities for about half its export revenue. Its largest trading partner is the U.S.
The Canadian dollar weakened as much as 0.6 percent to C$1.1688 per U.S. dollar, from C$1.1624 yesterday. It last traded at C$1.1664 at 9:22 a.m. in Toronto. One Canadian dollar buys 85.73 U.S. cents.