The dollar was down 0.9 percent at 117.71 yen, moving back towards a one-month trough of 115.85 set recently. It had risen as far as 118.87 overnight after investors sold the Japanese currency as a precautionary move in case the BOJ eased.
The euro fell 0.8 percent to 136.08 yen, back towards a three-month low of 134.70 touched on Friday.
"The reason the yen is holding up pretty well is on the back of the BOJ and the fact that they haven't taken any additional action despite the fact that they've brought down their inflation forecasts," said Ian Stannard, European head of FX strategy at Morgan Stanley in London.
With the BOJ meeting out of the way, market focus will now shift fully to the European Central Bank, which is widely expected to unveil a quantitative easing programme on Thursday in a bid to ward off deflation and kick-start growth.
That kept investors away from the euro, which at $1.1573 was not far from an 11-year trough of $1.14595 set last week.
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Stannard, however, said there had been a scaling back of short euro positions over the past week as investors showed some caution ahead of the ECB. QE, he said, had been largely priced into the single currency.
"Let's just hope Mr Draghi and the ECB don't disappoint or things could get ugly pretty quickly," Michael Hewson, chief market analyst at CMC Markets, said in a research note.
Sterling edged up 0.2 percent to $1.5162, helped by hopes for a brighter set of British labour data, due at 0930 GMT.
With markets having pushed back their forecasts for when the Bank of England will raise interest rates, the minutes of the central bank's latest meeting, also due at 0930 GMT, were in focus too.