"At some stage Japan being considered for the Rugby Championship would be on the table but, clearly, that has to come at a time when they were able to compete," Tew told the Herald.
"Right now Sanzaar is focused on ensuring the Sunwolves can compete in Super Rugby. That's the first step, and they've clearly got a way to go despite their win over the Blues in the final game."
The issue with that theory is, at present, the Sunwolves are not entirely reflective of Japanese rugby. Their established domestic Top League, backed by corporate giants like Toyota, Toshiba and Ricoh, attract a wealth of foreign talent which essentially hamstrings the Sunwolves' ability to do likewise.
In their last test against Japan in 2013, a second-string All Blacks team eased to a 54-6 victory in Tokyo. But Japan has since proved with their shock upset of the Springboks at the 2015 World Cup they are capable of punching above their weight.
"The obvious difference between one or two good performances at the World Cup is year in, year out you've got to play home and away against the best countries in the southern hemisphere," Tew said. "That's a big difference in terms of depth, performance and expectation.
"They are not necessarily directly linked but I don't think you would be wise to contemplate the Japan national side coming into the Rugby Championship until we get the Sunwolves properly embedded into Super Rugby because part of that responsibility sits with the JRFU which is across both teams.
"They were always on notice that the Sunwolves needed to be up and running and performing well and some things have to be done to make sure that happens."
The Sunwolves have a license for five years through to the end of the next Sanzaar broadcasting deal in 2020. After two seasons, they have three wins and one draw from 30 games.
Tew said Japan's potential had to be balanced with a dose of realism. The Rugby Championship remains a jewel in Sanzaar's crown and adding new participants could weaken the product. To this point, the Six Nations has also shown no appetite to open its doors to Georgia.
The reality of including Japan involves adding another time zone and more travel which would put the squeeze on elsewhere.
"Their entry into a regular competition is a matter of time but I'm not in a position to give you a timeframe," Tew said.
"Nothing is impossible but it does add another layer of complexity. Realistically, unless the calendar changes, you'd be looking at playing less games against the others to accommodate anybody new. You can't keep adding. They're all things you have to take into account.
"No-one is shutting the door on that happening but as 'Gus said it's not just Japan we need to be taking into account.
"We've got USA and Canada; Georgia in Europe and so how do you find regular competition for those teams to develop and be truly credible threats at Rugby World Cup? That's the challenge for World Rugby. Everyone knows the calendar is crowded; the need for money is intense and the world is a big place when you've got to fly folk around."
Discussion about Japan also raises plight of the Pacific Islands, who continue to be overlooked when it comes to Super Rugby. Speculation appears positive about possibly basing a team out of Fiji come 2020, but Tew flagged familiar concerns.
"If we're going to expand in this part of the world the Pacific Islands are a consideration but they have to come back and prove its right for them and the competition. You've got to look at the high performance structures; the depth, coaching, infrastructure, commercial and financial considerations. We can provide the ruler for that stuff but they've got to develop those things themselves."
