South Korea's Bo Bae Song birdied the final hole for a 7-under 65 and a one-stroke lead after the second round of the Mizuno Classic on Saturday.
Song had six birdies in a front-nine 30, and then had two birdies and a bogey on the final nine holes for an 11-under total of 133 at Kintetsu Kashikojima.
"My putting was good on the front nine, all single putts," Song said. "But it was not as good on the back nine. I three-putted on par-5, 13th hole, even though my shots were good."
Song's 65 tied her career-low she previously set back in 2007.
Japan's Akane Iijima equaled the course record with a 64 and South Korea's In-Kyung Kim went round in 65 for a share of second place, while Rui Kitada of Japan shot a 66 to lie one stroke further back in the event sanctioned by the LPGA Tour and Japan LPGA.
Kim, a three-year member of the LPGA Tour and two-time tour winner, had a bogey-free, seven-birdie performance.
A group of eight players were tied for a share of fifth on 136, including defending champion Jiyai Shin (67), Japanese star Ai Miyazato (67), 2007 winner Momoko Ueda (68) and first-round leader Brittany Lang (70) of the United States - the lone non-Asian player in the top 12. Top-ranked Lorena Ochoa was four under after a round of 69.
