TOKYO, July 6 (Reuters) - Japanese government bond prices rose on Monday amid a flight-to-quality triggered after Greeks rejected austerity in Sunday's national referendum and pushed Athens closer to an euro zone exit.
However, JGB gains were modest as the market took a calm view about the coming chapters of the Greek debt saga and its potential implications on markets worldwide.
The benchmark 10-year JGB yield fell 2 basis points to 0.46 percent. The yield has moved between a record low of 0.195 percent struck in January and a nine-month peak of 0.545 percent in June.
The 20-year yield edged down a basis point to 1.22 percent.
"If it were to happen, a Greek exit will be a long, drawn-out procedure. Furthermore, Greece might ultimately opt to stay in the euro if their politics cannot cope with disorder in the domestic economy," said Chotaro Morita, chief rates strategist at SMBC Nikko Securities in Tokyo.
"Whichever the scenario, the global markets cannot keep reacting to each step of a long process - even the European markets are unlikely to show a crash-and-burn type reaction later in the day."
The euro was down 0.5 percent at $1.1047 but managed to hang above a recent low of $1.0955, a four-week trough plumbed late in June.
Monday saw the Osaka Securities Exchange (OSE) launch trading in the revamped 20-year JGB futures. The 20-year futures went into hiatus in 2002 due to limited usage and were relaunched in April 2014 only to be plagued again by a lack of trades.
In an attempt to make the futures more attractive to users and spur more trades, the OSE lowered the minimum trading unit to 0.01 yen from 0.05 yen and narrowed the range of deliverable bonds for better liquidity.
As of mid-morning, volume for 20-year futures <0#2JTB:> was 39 lots, compared to around 8,500 lots in the better traded 10-year futures.
In theory, the changes should provide greater hedging opportunities for investors as more 20-year and 30-year "super long" JGBs are issued, although participants said it was too early to say if the futures will find more users after the face lift.
The market impact from the changes in 20-year futures will be limited unless the Bank of Japan decides to omit recently issued super long issues from the list of JGBs it purchases at its debt-buying operations, strategists at Mitsubishi UFJ Morgan Stanley Securities said.
The BOJ regularly buys a large amount of JGBs from across the yield curve as part of its quantitative easing scheme. (Reporting by Shinichi Saoshiro and Tokyo markets team; Editing by Richard Borsuk)