Born in Hobart and having lived in four other Australian states or territories because of his nomadic rugby career, Coleman's Tongan roots are often overlooked.

The Melbourne Rebels hard man's father was Ikale Tahi Test captain Pau'u Afeaki, who died when his son was 12.

By that stage, rugby was in Coleman's blood. His passion grew as three cousins became Test forwards - Rodney Blake (Australia), Inoke Afeaki (Tonga) and Ben Afeaki (New Zealand).

"That's the reason I play rugby," Coleman told journalists in Odawara.

"You have the old man play rugby for Tonga and you've got three-four cousins that have played professional rugby. So as a youngster you always look up to them and think 'I want to play rugby, I want to be better than them'.

"I wanted to get out there and find out why they like it so much. Why are they doing that?"

The aggressive 27-year-old was a standout in his debut Test season of 2016 and became one of the first names pencilled in by coach Michael Cheika for three years.

However, injury issues and the form of Izack Rodda and Rory Arnold could see him consigned to mainly a bench role in Japan.

Coleman was relieved to simply win squad selection for his first World Cup, which is his last rugby assignment before leaving for English Premiership club London Irish.

"The gold jersey means so much to me and it wasn't a decision, you know, just going overseas," he said.

"I was probably a little bit emotional after that Samoan game (in Sydney this month) because I knew it would probably be my last game in Australia for a while.

"I'm thankful to be here. It's been a bumpy ride, especially this year through injury."

As well as paying tribute to his father, Coleman said he would have the names of mother Jennifer and one-year-old daughter Fia on his wristbands for Saturday's Test in Sapporo.

Australian Associated Press