In recent years, the international scene has mostly showcased players with multiple heritages moving across from tier-one sides such as New Zealand and Australia to play for nations such as Samoa and Tonga in particular.
Koloamatangi went the other way, switching from Tonga to Australia before last year's Ashes tour after previously representing the Mate Ma'a on 10 occasions, including the 2022 World Cup.
"I just want to experience everything. I was lucky enough to play for Tonga in the last World Cup in England," Koloamatangi said
"I think if Australia comes calling, it's not something you can turn your back on. It's probably the best team you can make, and it's something I want to look back on, knowing I always dreamt of doing it as a kid."
Koloamatangi, who will join St George Illawarra next season from South Sydney, has a deep appreciation for both nations and does not regard his choice this time as valuing one side of his heritage over the other.
The 28-year-old will play prop against Fiji at Suncorp Stadium on Sunday night as a proud Kangaroo.
"I played for Tonga, I've play Origin, and I wanted to play for all the nations that I am eligible for," he said.
"It's something I'm really proud of because I'm just as Australian as I am Tongan. I was born Australian and my dad's Tongan. For me, I just wanted to experience a World Cup in the Australian colours, and I've got a lot of great mates here too."
Koloamatangi admits it was "a tough decision" but the classy response of Tonga coach Kristian Woolf reassured him.
"I spoke to Woolfy and he was very grateful for the conversation I had with him. He was respectful and accepted my decision. I have no regrets," Koloamatangi said.
"I loved my time with Tonga, with the atmosphere they get and the crowds they get.
"They're such a small country, and seeing them on the big stage now I've been being blessed to be a part of it."
There is a chance Tonga and Australia could meet in the World Cup semi-final or final.
Tonga's 30-12 win over England in the opening round has them on track to reach the final-four.
"I watched the game last week and was so proud of how they turned up for their nation," Koloamatangi said.
"Obviously, I want Australia to win, but if we weren't to win, I'll be cheering the Tongans all the way. I wish nothing but the best for them."
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