Gunter was immense as a late try to Wallabies debutant Connal McInerney clinched a 32-23 victory for Australia over Japan in Oita on Saturday.

After stunning Scotland and Ireland en route to the 2019 World Cup quarter-finals in front of their delirious home fans, the Brave Blossoms threatened another famous boilover after pulling to within four points of the Wallabies with the clock winding down.

Asked by AAP if Japan should be welcomed into a new-look Rugby Championship after cementing their place in the world's top 10, Gunter's response was an emphatic yes.

"One hundred per cent, mate," Gunter said.

"Today was our first game from being apart, being separated - we all had a bit of time off - and that's our first game back and we did really well.

"Obviously we didn't get the result that we wanted but it shows that the Japanese level of rugby now is very competitive.

"Like, we are taking it to tier-one teams. We don't look at them as though they're going to smash us. We look at them as like we can beat these teams week in, week out."

The Rugby Championship currently features Australia, New Zealand, South Africa and Argentina, with SANZAR this year announcing that the world champion Springboks had committed until at least 2030.

The Boks opted out in 2020 because of the global pandemic, raising doubts after their ongoing participation amid speculation that South African Super Rugby franchises were considering joining an expanded PRO14.

But while South Africa is in the same time zone as the UK, Japan also seems a good fit for the southern hemisphere's Rugby Championship.

"The other thing is, too, we play very exciting rugby," Gunter said.

"We like to keep the ball in play and I think that's what fans want to see.

"They want to see the ball in play, non-structured rugby, offloads, the kicking game.

"So 100 per cent Japan can easily compete with these teams at that level so they should be invited to those championship games and stuff.

"If you ask anybody, mate, everyone's keen to see the Japanese style of rugby."

Wallabies captain Michael Hooper said it was above his pay grade to make such calls but claimed - tellingly - that the pace of Saturday's game was "more up-tempo than some of the Rugby Championship games".

"Definitely not the New Zealand games," Hooper said.

"(But) Japan are just a side that are improving out of sight."

Wallabies coach Dave Rennie said the only way was up for the Brave Blossoms.

"They're a good side. They've got outstanding staff who have developed genuine depth," he said.

"They're only going to get better, I think.

"They're certainly worthy of where they are sitting in the world and it's certainly great that they're playing a lot of tier-one nations now compared to what they were doing two or three years ago."

Australian Associated Press