Japanese government bond futures hit a 5-1/2 month high on Monday, extending gains after last week's soft consumer price data bolstered expectations the Bank of Japan will not raise interest rates anytime soon.
JGBs staged a fierce rally on Friday after data showed that Japan's nation-wide core consumer prices, based on new calculations reflecting trends in household spending, rose a smaller-than-expected 0.2 percent in July from a year earlier.
Despite some wariness about the pace and scope of the rally, JGBs extended their gains on Monday, with futures rising to an intraday high of 134.78 the highest level for a lead futures contract since March 10.
In addition to JGBs, three-month euroyen futures also rallied, with the March contract rising 0.030 to 99.350 as of 0749 GMT.
"The price action in euroyen futures suggests the market thinks that there might not be a rate rise by the end of the year, nor by the end of the current fiscal year (next March)," said a trader at a European investment bank.
The September 10-year JGB futures contract pared some of its gains in late trade to finish the day session up 0.29 point at 134.47
Both the five- and 10-year yields fell to 5-1/2 month lows, or their lowest levels since early March.
The five-year yield fell as low as 1.100 percent before pulling back to 1.130 percent in late trade.
The benchmark 10-year yield dropped as low as 1.665 percent but later pulled back to 1.680 percent, still down 2.0 basis points on the day.
Despite the rally in JGBs and euroyen futures, a Reuters poll last week showed that some market players still think the BoJ - which raised the key overnight call rate in July to 0.25 percent from zero - may raise interest rates again by the year-end.
Eight out of 20 market players and analysts polled by Reuters on Friday after the release of CPI data said they expect the BoJ to raise the key overnight call rate by the end of the year, while another five expect it to raise interest rates in the January-March quarter.
Looking ahead, the Finance Ministry plans to offer around 1.7 trillion yen ($14.51 billion) in two-year JGBs on Tuesday.
Investor demand could be tepid, since the coupon rate could be set at 0.6 percent, down from 0.8 percent at the previous two-year auction in July, said an analyst for a Japanese brokerage house.
But even if the two-year auction turns out to be mediocre, that is unlikely to be enough to trigger a sharp sell-off in JGBs in general, the analyst said, adding that the bond market was supported by factors such as concern about how a slowdown in the US economy may affect Japan.
The two-year yield stood at 0.635 percent in late trade after dipping as low as 0.615 percent.