First-round leader Shiho Oyama, Yuki Ichinose and Mamiko Higa lead the Mizuno Classic field at 8-under 136 after Saturday's second round in Shima-Shi, Mie, Japan.
The three JLPGA members lead Asako Fujimoto and LPGA Tour member Brittany Lincicome by one stroke.
Oyama maintained her lead at the Kintetsu Kashikojima Country Club after another 4-under round of 68.
"I came this far so I'm definitely going for it tomorrow," Oyama said. "My caddie this week caddied for Bo-Mee Lee and she won last week so I think the luck is on my side. Hope to make the best out of tomorrow with my partner."
Ichinose and Higa both shot 6-under 66s to climb up the leaderboard after starting the day tied for 11th.
American Brittany Lincicome and Japan's Asako Fujimoto are tied for fourth at 7-under. Lincicome avoided a bogey on the par-5 18th when she overshot the green on her third stroke. She then pitched her fourth shot 12-feet past the hole but drained the putt to save par and finished with a 4-under-par 68.
"It's nice to be up there," Lincicome said. "Being in the last group always adds a little pressure. Not being in the last group, I think I play best or I've won the most from. It will be fun to go out tomorrow. If I keep doing the same things I've done the last two days, it should be really close. It should be a good Sunday."
A group of four is tied for sixth at 6-under, including Taiwan's Teresa Lu, Japan's Junko Omote and South Korea's Chella Choi and Eun-Bi Jang.
American Stacy Lewis, the tournament's defending champion and No. 3 in the Rolex Rankings, shot a 4-under 68 and is in a five-way tie for 10th at 5-under 139.
Also among those tied with Lewis is Japan's Yumiko Yoshida, who fired a 7-under 65, representing the best round of the day.