The current world number one Ryu So-Yeon, also of South Korea, finished the first round in a disappointing 23rd place after hitting one-over par 73.
Ji scored six birdies in a bogey-free round to keep a three-shot lead over compatriot Kim Sei-Young, American Megan Khang and former world No 1 Ariya at the Miramar Golf Country Club in New Taipei city.
Ji said she had changed her swing to adapt to the conditions.
"I think just a good day. I'm just more relaxed with the weather. That makes it a lot easier for when I play," she added.
Kim, who had two bogeys and five birdies, aims to pick up her second victory on the LPGA Tour but said it had been a "tough day".
"We got a lot of rain, and on a couple of holes, really gusting wind. It was tough to judge distance and how to take the club," she said.
Taiwan's Lee Min carded a two under par 70 with four birdies and two bogeys to share a place with four others and was the best performing local player of the day.