The 5-year yield ticked up 0.5 basis point to 0.185 percent, moving further from a nine-year low of 0.175 percent hit on July 12. The Ministry of Finance is to auction 2.5 trillion yen of five-year bonds on Thursday.
The benchmark 10-year yield also inched up 0.5 basis point, to 0.770 percent, not far from its nine-year low of 0.755 percent touched last week.
"We don't expect a sustained rise in yields because ... regarding Europe, the stress situation should continue," said Yuya Yamashita, rates strategist at JPMorgan.
"Although yesterday (Federal Reserve Chairman Ben) Bernanke's testimony didn't show concrete indication of QE3, the possibility remains relatively high."
Bernanke offered a gloomy view of the US economy's prospects on Tuesday, but provided few concrete clues on whether the central bank was moving closer to a fresh round of monetary stimulus.
Market participants had expected further US government bond buying by the Fed would spur the Bank of Japan to step up its monetary easing, boosting JGBs.
* Yamashita said he was underweight 5-year JGBs and overweight 8- to 10-year debt.
"BoJ Governor (Masaaki) Shirakawa rejected a cut in the IOER (interest on excess reserve). As long as the level of IOER is maintained at 10 basis points, then the downside of the 5-year yields, or less than 5-year yields, should be limited."
"If we think that the bull environment continues for a while, then there is more downside in the 8- to 10-year yields. That's the rationale of the strategy."
The 10-year JGB futures were unchanged at 144.28, holding just above their five-day moving average at 144.27.
Yields on 20- and 30-year bonds were steady, at 1.565 and 1.775 percent, respectively.