The yield on the benchmark 10-year Japanese government bond briefly hit 0.505 percent on Tuesday, breaching a cap set by the Bank of Japan last month for a third straight trading day.
Many investors sold JGBs on speculation the bank could once again decide to taper its relatively loose policy at its ongoing board meeting.
But the BOJ responded by buying a massive amount of bonds, pushing the yield on the 10-year issue back down. The yield ended the day at its upper limit of half a percent.
The bank decided in its December meeting to allow the 10-year yield to move in a range of plus or minus 0.5 percent. The earlier band was plus or minus 0.25 percent.
The central bank conducts unlimited 10-year bond buying operations at a fixed yield of half a percent on a daily basis to prevent a rise in the rate.