TOKYO, Aug 17 (Reuters) - Benchmark Japanese government bonds edged down on Thursday, supported by decent demand at a five-year JGB sale though cautious ahead of Friday's buying operations by the Bank of Japan.
The 10-year cash JGB yield added one basis point to 0.045 percent, while the September 10-year JGB futures contract finished down 0.08 point at 150.60.
The BOJ trimmed its buying of five- to 10-year JGBs to 440 billion yen ($4.01 billion) in its purchase operation on Wednesday, from 470 billion yen in the previous four operations.
"The BOJ took advantage of thin liquidity during the summer vacation season to reduce its buying with minimal market impact, and it's possible they might do it again," said a fixed-income fund manager at a foreign asset management firm in Tokyo.
On Friday, the BOJ will purchase 200 billion yen to 300 billion yen of 1-3 year JGBs, 250 billion yen to 350 billion yen of 3-5 year JGBs and 350 billion yen to 550 billion yen of 5-10 year JGBs.
On Thursday, the Ministry of Finance auctioned 2.2 trillion yen of 5-year JGBs with a 0.1 percent coupon.
Some 69.6951 percent of the bids were accepted at the lowest price of 100.88. The sale drew bids of a solid 4.46 times the amount offered, though below the previous sale's bid-to-cover ratio of 4.85 times.
The five-year cash JGB was untraded, while the two-year JGB yield was flat at minus 0.120 percent.
($1 = 109.8600 yen) (Reporting by Tokyo markets team; Editing by Biju Dwarakanath)