After opening with 67s, the trio are now 13-under around Damai Indah Golf's 6,545-metre (7,160-yard) Bumi Serpong Damai course in pursuit of their first OneAsia or Japan Tour title as the U.S. $1 million tournament is co-sanctioned by both.
Japan's Michio Matsumura (67) is a shot behind, while Ouyang Zheng eagled the last to grab sole fifth place at 11 under with a 67. Aussie Rhein Gibson (75) -- holder of the world record low score by a professional -- was at 10 under with Chinese teenager Li Haotong.
Park, who celebrated his son's first birthday on Friday, was delighted with his effort despite feeling his driving was not up to scratch.
"My boy is one year old today so this is for him," said 30-year-old, whose only blemish was a bogey on the fifth. "My target today was to make a birdie on every par five and I managed to do that. My putting was also very good, so I am happy."
Pagunsan, a winner at this course in 2007, also credited a hot putter for his blistering round.
"The greens are very different from when I won here -- they go up and down a lot more -- but I managed to put it close and that was important today," he said.
The runner-up at this event last year, Pagunsan said he has spent more time on his physical fitness this year in a bid to go one better.
"I am in much better shape this year," the 35-year-old said. "I hope I can get the results to show for the work."
Playing in the afternoon, Tokimatsu set up his great round with some devastating tee shots -- he has only missed one fairway in two days -- and thinks he can go even lower.
"I'm very pleased, but for the weekend I want to do better," he said.
The round of the day belonged to Aussie rookie Jack Wilson who fired nine birdies in his career-best 63, to offset an opening-round 73.
"I hit it good yesterday but couldn't buy a putt," he said. "Today was one of those rounds that is out of the box. I hit it really good again, and my local caddie came up with some great reads -- which certainly helped in making the majority of my birdies."
With the cut at minus three, headline act Y.E. Yang, Asia's only Major winner, just squeezed in after a second-round 67 left him at four under.
Lismore's Rhein Gibson is the leading Australian in a share of 5th position and three from the lead while David McKenzie and New Zealander David Smail are one shot further back in 7th place.