Japan is the first Asian country to host the tournament, now in its ninth edition, with a total of 48 games at 12 venues across the country.

Of the 20, eight teams will advance to the knockout stage starting October 19 and the final will be held in the port city of Yokohama, south of the capital, on November 2.

With 96 per cent of the 1.8 million tickets already snapped up, organising committee chairman Fujio Mitarai was confident that the host nation could achieve one of its major goals - to have all 48 games played in front of "completely full stadiums."

Japanese fans' enthusiasm for the tournament has already been seen with an opening training session by Wales, who are ranked fifth in the world rankings, attracting as many as 15,300 people in Kitakyushu on the southern island of Kyushu on Monday.

"Japan has comprehensively proven that it will be the best of hosts, welcoming the world's best players and 400,000 international visitors with open and welcoming arms," World Rugby chairman Bill Beaumont told a news conference in Tokyo.

"The welcome that the teams have received has been nothing other than magnificent, truly special," Beaumont said emphatically.

"Never has a tournament been so eagerly anticipated and never has a host nation been so excited to embrace our sport.

"The world rugby men's rankings certainly suggest that this will be a very compelling and competitive rugby World Cup," he added.

The Japan Brave Blossoms will take on Russia at Tokyo Stadium on Friday, while defending champions New Zealand are set to kick off their campaign on Saturday against the fourth-ranked South Africa.

Since beating Australia 34-17 in the 2015 World Cup final to claim back-to-back World Cup titles and a record third crown overall, All Blacks head coach Steve Hansen has lost top players such as then-captain Richie McCaw and Dan Carter, who won the World Rugby player of the year award in 2015.

"The key is making sure we prepare well as we try to do something that has never been done before," Hansen said.

"New Zealand, Wales and now Ireland have occupied top spot in the standings over the last six weeks or so, nearly doubling the number of teams who have been at top since the rankings began in 2003, which is exciting."

Australian Associated Press