The Nikkei 225 index has closed at 10,081.56, down 134.15 points, on a late wave of profit-taking after opening gains failed to trigger follow-through buying.
The dollar was at 120.41 yen in Tokyo trading, up from 120.20 in late New York trading on Friday. It was 0.8933 against the euro, compared with 0.8943 in New York.
Dealers say the dollar was little changed in narrow ranges in mid-afternoon trade ahead of the partial holiday for financial markets in the US today.
Government bond yields were lower, with government bond No 233 yielding 1.2 per cent, compared with 1.275 per cent on Friday; and the No 234 issue yielding 1.3 per cent, against 1.3 per cent on Friday.