September 10-year JGB futures were up 0.04 point at 151.50, with caution before Federal Reserve Chair Janet Yellen's speech at a central bankers' meeting on Friday preventing further gains.
The finance ministry sold 500 billion yen ($4.98 billion) of off-the-run JGBs on Thursday in a regular auction designed to enhance liquidity in the market.
The benchmark 10-year JGB yield was unchanged at minus 0.085 percent.