SANZAR, the organization that runs Southern Hemisphere rugby, officially approved Japan's participation in Super Rugby from 2016 at an executive committee meeting on Thursday.
Argentina's participation, expanding the number of teams at Super Rugby to 18, was also confirmed by SANZAR
The confirmation is the final stage of formalities and paves the way for the Tokyo and Buenos Aires-based franchises to start contracting players and staff ahead of their historic entry to Super Rugby in a little over 12 months from now.
The Japanese team will be based at Tokyo's Prince Chichibu Memorial Rugby Ground with three home games per season to be played at the Singapore Sports Hub.
Japan, currently ranked 10th in the world, will host the 2019 Rugby World Cup.
"It gives us great pleasure to welcome the JRFU (Japan Rugby Football Union and UAR (Union Argentina de Rugby) who will join the Kings from South Africa as Super Rugby prepares to expand into a bold and exciting new era." SANZAR chief executive Greg Peters was quoted as saying on SANZAR's official Website.
"As Top 10 ranked rugby nations with established high performance level leagues and over 100,000 players each, there is no doubt as to Japan and Argentina's rugby readiness and passion for the sport."
"With a heritage stretching back some 115 years, Japan also offers tremendous infrastructure and an active fan base that we view as pivotal to the ongoing sustainability of the team."
He added: "Japan has also been the focus of strategic investment by the International Rugby Board (now World Rugby) and we view the region as a high growth, high potential sports and economic market with the 2019 Rugby World Cup, the 2020 Olympic Games and now Super Rugby on the imminent horizon."
Tatsuzo Yabe, chairman of the JRFU said, "It is a great pleasure and honor to be able to announce the historical decision of Japan's entry to Super Rugby."
"It is absolutely essential for us to participate in the competition as we move toward a successful Rugby World Cup here in 2019.
"Joining the world's highest international league is a challenge that will require significant transformation and tremendous efforts by us. However, it will certainly bring innovation to not only Japan, but also the Asian region as a whole," he said.
"We are also convinced that participating in Super Rugby will encourage greater interest in our domestic rugby and it will become a big dream and goal for those who play rugby in Japan — especially younger generations — to compete at this level."
He added: "We believe that such positive development will be a driving force for Japan rugby to move forward on the world stage and we will continue to make every endeavour to be successful at this level as we look toward Super Rugby in 2016, the 2019 Rugby World Cup and beyond."
The JRFU has also forged a relationship with the Singapore Rugby Union and Singapore Sports Hub that will see the state-of-the-art venue host three games per year, delivering Super Rugby to new Asian audiences.