KO OLINA, 18 Apr 2015 (AFP) - Kim, who notched her first LPGA victory in just her second start as a tour member at the Pure Silk-Bahamas this season, had shared the overnight lead with compatriot Kim In-Kyung.
But a round that included five birdies and three bogeys on Friday saw her edge ahead by one stroke with a 12-under par total of 204.
Kim In-Kyung had four birdies and three bogeys in her one-under 71 for 205.
It was a further stroke back to world number three Park In-Bee, who signed for a three-under 69.
Two more South Koreans occupied fourth and fifth, Jenny Shin posting a two-under 70 for 208 and Chella Choi signing for a 71 for 209.
Defending champion Michelle Wie was eight adrift after a one-over 73, part of a group of six players on four-under 212.
Kim Sei-Young admitted that she was more comfortable chasing the lead, and she said she'd try not to put any extra pressure on herself on Saturday.
She took a three-shot lead into the final round of the ANA Inspiration, the year's first major earlier this month, but fired a final-round 75 to finish two shots out of the playoff won by Brittany Lincicome.
"I felt a lot of nerves during that tournament," she said. "But tomorrow I'm going to try to do the same thing I've done the past three days here and try to enjoy the rounds.
"I think I'm going to be able to come out with a different outcome tomorrow."
All of the top three players talked about the difficult windy conditions.
"It was tough wind, but I was hitting the ball kind of everywhere, especially on the tee," Kim In-Kyung said. "I didn't know what was happening. I was pushing it to the right a few times and I was (feeling) pressure reading my putting on the greens."
Kim In-Kyung is chasing a fourth LPGA title but her first since 2010 and she was looking forward to a chance to challenge on Saturday.
"I've been playing well the last few weeks and working very hard this offseason," she said. "Where I'm at now, I'm very comfortable, actually."
Leading third-round scores on Friday in the LPGA Tour's LOTTE Championship (par-72):
204 - Kim Sei-Young (KOR) 67-67-70
205 - Kim In-Kyung (KOR) 65-69-71
206 - Park In-Bee (KOR) 67-70-69
208 - Jenny Shin (KOR) 68-70-70
209 - Chella Choi (KOR 70-68-71
210 - Ai Miyazato (JPN) 70-69-71, Paula Creamer 69-69-72
212 - Cristie Kerr 69-76 67, Kim Hyo-Joo 69-73-70, Morgan Pressel 69-72-71, Beatriz Recari (ESP) 69-71-72, Michelle Wie 70-69-73, Lee Mi-Rim (KOR) 69-69-74
213 - Sandra Gal (GER) 70-72-71, Mika Miyazato (JPN) 71-71-71, Lin Xi Yu (CHN) 69-72-72, Lee So-Young (KOR) 71-69-73, Brittany Lincicome 73-67-73, Haru Nomura (JPN) 69-70-74
214 - Alison Walshe 74-73-67, Lee-Anne Pace (RSA) 72-71-71, Pornanong Phatlum (THA) 71-69-74