Jiyai Shin of South Korea and Ayako Uehara of Japan both shot 4-under 68 to lead the Mizuno Classic after the first round Friday.
Shin had three straight birdies on the front nine and added two more after the turn, offsetting a bogey at No. 9. She won at Kintetsu Kashikojima Country Club in 2010 and 2008.
American Angela Stanford and defending champion Momoko Ueda of Japan were in a group of six tied for third at 3-under.
Inbee Park of South Korea shot 70 and was in a group of 10 tied for ninth. Park opened the LPGA Tour's Asian Swing with a victory in Malaysia and finished second last week in Taiwan.
World No. 1 Yani Tseng of Taiwan was tied for 19th after a 71.