Japanese rugby chiefs on Tuesday announced a shake-up of eligibility rules aiming to give local players more time on the pitch but casting doubt over the future of naturalized internationals. Foreign-born players have played a prominent role for Japan's national team, who stunned South Africa at the 2015 World Cup and reached the quarterfinals on home soil four years later. But Japan Rugby League One said domestic clubs will have to field at least eight players who were raised in the country from the 2026-27 season. Exceptions will be made for players who have more than 30 caps for Japan. The league said the change was needed to encourage more Japan-born players to pursue professional careers. More than half of the players who started last season's Japanese championship final were born overseas. They included former Japan captain Michael Leitch, who has won 87 caps since making his international debut in 2008. Leitch was born in New Zealand but moved to Japan at the age of 15 to attend high school as part of an exchange program. Under the current rules, Japanese clubs must field at least 11 players eligible to be selected for the country's national team. This group can include foreign-born players who have been continuously registered with a Japanese club for four years. Under the new rules, a new category will be created for players who spent at least six years in the Japanese education system before going to high school. Teams must field at least eight of these players at any one time, squeezing out foreign-born Japan internationals who do not meet the criteria. Were the rule to come into force today, several current Japan internationals including center Dylan Riley and lock Warner Dearns would miss out.