TOKYO, July 10 (Reuters) - The five-year Japanese government bond yield hit its lowest level in nearly four years on Friday as Japan banks shifted money into short- and medium-term maturities, helped by growing speculation that the Bank of Japan will decide next week to extend fund-supply steps beyond September.

The five-year JGB yield fell a basis point to 0.655 percent JP5YTN=JBTC, the lowest since September 2005. (Reporting by Satomi Noguchi; Editing by Rodney Joyce)