TOKYO, Jan 30 (Reuters) - Japanese government bonds edged down slightly on Monday as investors awaited the next day's Bank of Japan policy announcement and monthly JGB-buying plans, though market sentiment was underpinned by strong demand at a 2-year auction.
The 10-year JGB yield added half a basis point (bp) to 0.080 percent, while 10-year JGB futures slipped 0.07 point to 149.93.
The 20-year yield rose 0.5 bp to 0.655 percent , while the 2-year yield bucked the trend and slipped 1.5 percent to minus 0.220 percent after sold results at a 2-year sale.
The BOJ will release its bond-buying operation plans for February at 5:00 p.m. Tokyo time (0800 GMT) on Tuesday.
"After the BOJ's meeting tomorrow, JGB market participants are focusing on the BOJ's JGB purchase plan for the month of February, rather than its policy statement," said Naomi Muguruma, senior strategist, Mitsubishi UFJ Morgan Stanley Securities.
"The BOJ's operation desk will most likely make their February purchase plan like the most recent one," she said.
The BOJ's bond-buying operations have been in the spotlight in recent sessions. The central bank surprised dealers on Friday by increasing its purchases of 5- to 10-year bonds, which helped pull their yields away from 11-month highs touched earlier in the week.
The BOJ also surprised market participants two days before that, when it skipped buying shorter maturities.
Policymakers are widely expected to keep their monetary stance steady on Tuesday and seek to allay speculation of an early tapering of its massive stimulus, particularly with the central bank on course to buy the smallest amount of Japanese government bonds in more than two years in January.
The BOJ has purchased 8.25 trillion yen of JGBs so far this month, the smallest amount since October 2014. It is expected to refrain from buying on Tuesday, as it typically does on days when it makes policy announcements.
At the Ministry of Finance's sale of 2.3 trillion yen ($20.08 billion) of 2-year JGBs with a 0.10 percent coupon, 32.5719 percent of the bids were accepted at the lowest price of 100.545.
The sale drew bids of 5.19 times the amount offered, up from the previous sale's bid-to-cover ratio of 4.51 times. The tail between the average and lowest accepted prices narrowed to 0.004, compared with that of last month's offering at 0.006, indicating slightly stronger demand for the bonds.
($1 = 114.5700 yen) (Reporting by Tokyo markets team; Editing by Amrutha Gayathri)