The chance to tap into the vast Japanese market and improve the global appeal of the current three-nation tournament - which comprises of teams from Australia, New Zealand and South Africa - are among the key attractions for organisers.
The Super 12's $786million broadcast rights deal with Rupert Murdoch's News Corporation expires in 2005 and the South African New Zealand Australian Rugby alliance (SANZAR) is struggling in its present form to secure better terms.
Australia is already lobbying for at least one extra team, to raise its representation to at least four.
SANZAR officials are expected to open talks early next year on the prospect of revamping Super 12.
The World Cup has highlighted the need for second-tier sides to be offered avenues to play at higher levels and SANZAR officials are aware that they can foster southern hemisphere development through the Japanese option.
Entry to Super 12 would also boost Japan's bid to host the 2011 Rugby World Cup.
Other than Japan, a combined Pacific Islands team embracing Fiji, Tonga and Samoa has been mooted and Argentina has made an official approach to have a side in the series.
Building on the platform of this year's Rugby World Cup, Japan is lobbying to be included in the Southern Hemisphere's Super 12 series from 2006.
