Headed up by halfway co-leader Nasa Hataoka, Japanese players hold down the top six positions after the third round at Seta Golf Club in Shiga.
Hataoka retains a share of the lead following a second straight four-under-par 68, with Yuna Araki joining her in front after carding a brilliant 65 on Saturday.
Araki reeled off five consecutive birdies from the second to the sixth holes and joined Hataoka at 15 under with three more birdies on the back nine.
In-form world No.4 Miyu Yamashita is one stroke behind in outright third after last week's Maybank Championship winner and 2025 British Open champion also signed for a 68.
Shuri Sakima (69) is fourth at 12 under, one shot ahead of 2019 champion Ai Suzuki (70).
South Korean marvel Jiyai Shin, the reigning Australian Open champion, appears the only international in with a shot of crashing the Japanese party.
Chasing an incredible 67th worldwide professional win, Shin will start the final round five shots back in a tie for sixth after relinquishing her share of the halfway lead with a third-round 73.
Sayaka Takahashi (71) is also at 10 under with Shin.
Defending champion Rio Takeda, who has not been in contention all week, carded a 68 and will start the final round nine shots behind.
Any hopes of Minjee Lee continuing Australia's hot streak on the LPGA Tour evaporated after the world No.3 double-bogeyed the last hole for a lacklustre round of 74.
The highest-ranked player in the 78-strong field, Lee has tumbled to a share of 52nd at one under.
Lee's slip-up left rookie Karis Davidson as the top Australian at two under following an even-par 72.Â
Robyn Choi (73) is one over the for the championship and needs a big Sunday to advance from 65th in the live season-long point standings.
Only the top 60 after next week's penultimate event of the year will qualify for the $US11 million ($A17 million) Tour Championship in Florida from November 20-23.
