Joseph coached the Sunwolves last season and says the Super Rugby franchise will play a vital role in helping Japan prepare for the World Cup.
"In a World Cup year my core responsibility is to prepare the national team, especially as Japan is hosting the tournament," Joseph said. "Tony being at the helm as head coach will allow us to continue the hard work we invested last season, as well as prepare any players also in the national team for the World Cup."
Among the established Japanese players returning for the Sunwolves side are captain Michael Leitch, Keita Inagaki, Shota Horie, Fumiaki Tanaka and Kazuki Himeno, all of whom are expected to represent Japan in the World Cup.
Foreign-born returning players include Pieter Labuschagne and Grant Hattingh, the uncapped South African-born backrowers who have been included in Joseph's preliminary World Cup squad, and Australian lock James Moore.
Finding the right balance for players on Japan's national team will be crucial, with more players than usual eventually available to the Sunwolves.
Brown is also an assistant coach for the national team and says the players in the selection frame for the World Cup will need to prove themselves in Super Rugby.
The Sunwolves will play six home games in Tokyo and two in Singapore. They also play four games in Australia, two in New Zealand and one each in South Africa and Argentina.
- AP