As he does these days, Herbert the showman eagled the par-5 18th hole for the second day in a row to ice his remarkable five-shot triumph on Sunday.
Victory clinched a maiden Asian Tour and International Series title for the 29-year-old at the par-71 Caledonian Golf Club in Chiba.
Herbert closed with a seven-under-par 64 to reach 20 under for the week, daylight ahead of his playing partners, Japan's Yuta Sugiura and South Korean Younghan Song.
Victory completed an incredible run by Herbert, who was five shots behind the leader with three holes to play in the third round.
He engineered the 10-shot swing with two eagles in the last three holes on Saturday, followed by Sunday's 64 that included seven birdies and the eagle on the 18th.
The Victorian's reward was a move to the top of the Asian Tour Order of Merit, as well as the International Series rankings.
It was also his first international victory in almost two years, since winning the 2023 ISPS Handa Championship, also in Japan.
The Ripper GC star, who played a full season on the Asian Tour in 2016, started the day tied for the lead at 13 under alongside Sugiura and Song.
The 33-year-old Song immediately moved ahead with an eagle on the second hole, but Herbert hunted him down with birdies on the second, fourth and fifth.
Herbert made a bogey on the par-5 sixth and another at the 15th, but he was otherwise rock solid throughout and shut the door on the chasing pack.
"I was thinking about it down on the 18th green, that finish yesterday really set it up,'' Herbert said.
"Very happy with the way I played today, I think it was the low round of the day, so that's always going to make it hard to beat when you start the day tied for the lead."
A second-hand putter he found at a thrift shop in Korea last week was smoking hot again as he completed the round in just 23 putts.
But Herbert also credited a new driver he has been using this year. It has resulted in three top-10s on LIV Golf, where he is now fifth in the standings.
"I've played really well this year, and I think the driver was a big part of this success,'' he said.
"The way I've been playing this year, it's been building to get a win at some point. So, it's nice to get it done here, especially in Japan, which is one of my favourite places."
Herbert is not wrong. He signalled he was trending towards this win when he closed with a record-equalling 10-under final round to finish runner-up at last month's LIV Golf Mexico City.
American Cameron Tringale (66) rolled in a 15-foot eagle putt on the last to finish solo fourth at 14 under.
International Series Japan was the third of 10 elevated events on the Asian Tour calendar that form a pathway on to the LIV Golf League.Â
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