Japan national rugby team head coach Jamie Joseph countered observations Thursday that his squad for the upcoming Rugby World Cup contains several players born overseas by asking the question "what is a foreign player?"

Joseph named his 31-man squad for the Sept. 20-Nov. 2 World Cup earlier in the day, with 16 of the players who will represent host nation Japan at the tournament born overseas.

International rugby rules currently state that players who have lived in a country for 36 consecutive months are eligible to play for that nation, although this will be increased to 60 consecutive months effective as of Jan. 1, 2021.

Ten of the 16 foreign-born players on Japan's World Cup squad went to Japanese universities, including captain Michael Leitch, who was born in New Zealand but moved to Japan at the age of 15 to attend Sapporo Yamanote High School.

"My challenge is around the awareness and understanding of 'what is a foreign player?' " Joseph, who himself played nine times for Japan in 1999 after winning 20 caps for New Zealand's All Blacks, said at a news conference at the Japan National Press Club.

"I use Michael Leitch as an example," he said. "Michael is 30. He's been here since 15, and from my point of view, really, he is a Japanese man that was born in a different country, in terms of his contribution to the game of rugby. There are a lot of players like that nowadays. Certainly, when I played here 20 years ago, the foreign players were quite unique. When we played for Japan, it was a surprise. But in the past 20 years, I believe it's changed."

The emergence in recent years of several prominent multiracial athletes representing Japan has sparked debate over what it means to be "Japanese." Tennis player Naomi Osaka, who has a Japanese mother and a Haitian father, has won both the U.S. Open and Australian Open, while basketball player Rui Hachimura, whose mother is from Japan and father is from Benin, was selected ninth overall in the NBA Draft in June by the Washington Wizards.

Joseph said Thursday that he and his coaches weighed up several factors before deciding on their final squad, but described the players who made the cut as "the best in the country."

"I guess quite simply, really, if we have a player that is of similar skill and expertise, then we will always pick a Japanese national over a foreign player," he said. "What the foreign players give us is two or three things that Japanese players, in most cases, don't have.

"One is their physical size and presence. The second thing is their experience. A lot of our foreign players have played, like myself, from the age of 5, not 15. They've been developed differently, and therefore have different skill sets and experiences that are going to help us, particularly in moments of pressure which we will have at the World Cup."

Joseph insists that the diversity of his squad can be a rallying point as Japan attempts to negotiate a first-round group also including Ireland, Scotland, Samoa and Russia to reach the quarterfinals of a Rugby World Cup for the first time.

The Brave Blossoms' motto for the tournament is "One Team," and Joseph explained that the idea came from the players themselves.

"Right from the start, it was difficult to create a team that was going to have the belief and confidence to win at the World Cup unless we were aligning together," he said. "So after a series of camps and discussions, the leaders at the time came up with that as something that was important to them.

"What that meant was that, behind the scenes, everything that we are doing is accepting that we're from different cultures, but also accepting that because of that we need to work hard off the field, to ensure that we put our best foot forward to win test matches. That's where the team has come from."