South Korea's Bo Bae Song birdied the final hole for a 7-under 65 and a one-stroke lead in the Mizuno Classic.
Song had six birdies in a front-nine 30, then had two birdies and bogey on the final nine holes Saturday to reach 11 under at Kintetsu Kashikojima.
Akane Iijima (64) and In-Kyung Kim (65) were tied for second, and Rui Kitada (66) was 9 under in the event sanctioned by the LPGA Tour and Japan LPGA.
Defending champion Jiyai Shin (67) was 8 under in a group that included Japanese star Ai Miyazato (67), 2007 winner Momoko Ueda (68) and first-round leader Brittany Lang (70) _ the lone non-Asian player in the top 12. Top-ranked Lorena Ochoa (69) was 4 under.