Twice major victor Johnson carded a bogey-free seven-under 63 in the afternoon wave that included a birdie at 18 to grab a share of the lead with early starter Kirk, who stormed into the clubhouse with four birdies over the final six holes.
Harman, who has four top-10 finishes in four starts in the United States tour's 2017-18 season, teed off early at Waialae in Honolulu, and opened with back-to-back birdies at the 10th and 11th. On a far different course at Waialae, he had a stretch of three straight birdies in Friday's second round and closed with a 7-iron to 15 feet for eagle on the par-5 ninth.
Johnson got off to a hot start in his pursuit of Kirk, with birdies at the first three holes. He hit that out to 30 feet and two putts later had a snowman (8).
Johnson, victor of the 2007 Masters and the 2015 Open championship, broke away from the second-placed bunch at the final hole, despite finding a fairway bunker off the tee.
"My swing kind of felt better and better as the day went on".
Kirk, whose most recent victory was at Colonial in 2015, said a return to his old putting routines had paid off on the greens.
"I've probably been off long enough now that you never know what's going to happen", he said. "But I'll use that going forward". It takes about five or 10 minutes.
The leading duo was one stroke in front of a group of four players on a crowded leaderboard.
Vaughn Taylor, Kyle Stanley, Talor Gooch and Brian Harman are among those tied for third a shot back. After dropping his lone shot from a bunker on the par-3 seventh, Harman hit 7-iron from 172 yards to 15 feet on the par-5 ninth for a closing eagle.
Gooch rocketed out of the blocks with three straight birdies, finishing with eight birdies overall against two bogeys. For his third shot, he had a gap toward the front of the green (the pin was back left), but out of a fluffly lie, the ball came out high and hit more trees, bouncing left and settle near another tree.
The American was four under with two holes to play, but he endured a nightmare on the par-four eighth.
Japan's Daisuke Kataoka and Americans Peter Malnati, Matt Every and Tom Hoge all shot 65.
He rallied somewhat with a birdie at his final hole for a one-under par 69.
A year ago, it was because Justin Thomas shot 59 playing in the same group.
Thomas had five-times major champion Phil Mickelson's former caddie, Jim "Bones" Mackay, on his bag since his usual looper is unavailable due to injury.