Song, winner of last month's Japan Women's Open, reeled off six birdies in a flawless front nine and after bogeying the 13th, picked up two more strokes on Nos. 15 and 18 to reach 11-under 133 at Kintetsu Kashikojima Country Club in Mie Prefecture.

Akane Iijima sizzled with a bogey-free 64 to tie South Korea's Kim In Kyung (65) for second place, while former Women's World Cup winner Rui Kitada had a 66 to stand alone in fourth at 135 at the $1.4 million event co-sanctioned by the LPGA Tour and Japanese LPGA tour.

Defending champion Shin Ji Yai carded a 67 and was at 8-under in a group of eight players that also featured Ai Miyazato (67), 2007 Mizuno Classic winner Momoko Ueda (68) and American Brittany Lang (70).

World No. 1 Lorena Ochoa had a 69 and was at 4-under with Sakura Yokomine and eight others tied for 29th. JLPGA money leader Shinobu Moromizato closed at 2-over.