The 20-year-old from South Korea had seven birdies in the first 10 holes -- his 29 on the front nine matching the championship nine-hole scoring mark.
Kim joined Vijay Singh in 2003 at Olympia Fields, Louis Oosthuizen in 2015 at Chambers Bay and Neal Lancaster, who did it back to back in 1995 and 1996 at Shinnecock and Oakland Hills.
Coming in, however, there were bogeys at 13, 15 and 16 by Kim as the sun-baked course, hosting a US Open for the first time, showed its teeth.
"Those three bogeys really don't feel like bogeys because I barely missed it by a yard or two," said Kim, whose four-under par 66 put him at three-under 207 for the tournament.
"But major championship golf, US Open, really brings it out of you.
"Would have been nice to kind of par in and see that bogey-free or see one or two more birdies, but if you told me at the start of the day, I'd take that score."
One of Kim's bogeys came at the par-three 15th, playing Saturday at just 81 yards.
Birdies were proving even harder to come by there than they had in the first two rounds, when it played at 124 and 115 yards and saw three holes in one.
Kim said it still offered one of the few "realistic" birdie chances on the back nine because players are hitting a wedge off the tee.
"If you have a wedge, you have a chance to get it close and have a chance," he said.
No room for error
But at 81 yards, there's certainly no room for error.
"I mean, it was 76 yards, 80 something to the hole. You have four yards of green to work with," Kim said.
"You're long, you're dead; you're short, you're dead. It's a really simple wedge shot, but with the wind kind of going down to left, you've got to really hit it at the right time.
"It's a wedge. You don't want to bail out left. Then you have like a 40-footer down the hill.
"I just kind of got cute and kind of got plugged in the bunker. A bogey from 80 yards stats-wise isn't great, but definitely double is in play there."
Kim, who earned his second US PGA Tour title at TPC Summerlin last October and owns two titles on both the Asian Tour and Koran Tour, is chasing a first major title.
He's trying to follow the trail blazed by Asia's two male major winners: South Korean Yang Yong-eun -- who out-dueled Tiger Woods to win the 2009 PGA Championship -- and Japan's Hideki Matsuyama, the 2021 Masters champion.
Although he'd told himself not to watch the scoreboard, Kim admitted he couldn't help himself as the birdies were falling.
"It did catch my mind once I was seven-under, after 10 where, man, if I can keep this going, have a good finish -- and if the leaders kind of stumble -- I might have a chance to be really close up there on Sunday," Kim said.
"But it was a really short thought because I still had the hardest part of the golf course right in front of me."
