Tokyo - Yoshiro Mori announced his surprise resignation as honorary chairperson of the Japan Rugby Football Union, officials said on Thursday, just months before the country hosts the World Cup.
But the 81-year-old former prime minister will remain as president of the Tokyo 2020 Organising Committee for the Olympic Games.
Mori, who played a key part in bringing Asia's first Rugby World Cup to Japan, made the announcement after a JRFU board meeting on Wednesday, and said it was partially due to health concerns after suffering several bouts of surgery because of cancer.
"Mr Mori expressed his intention to resign because of his age and condition as well as his job at the Olympics and Paralympics," a JRFU spokesperson told AFP, adding that his replacement has not been decided. "But his resignation won't affect our hosting of the World Cup," which kicks off in September, the spokesman stressed.
"Mr Mori has said he will continue supporting the World Cup but expressed hope that young people should take the initiative in pushing for the sport," the spokesperson said.
Mori has reportedly said Japan "desperately needs a vision" for the sport post-World Cup, following news that the country will lose its Super Rugby franchise after 2020.
The Tokyo-based Sunwolves were introduced in 2016 to bring rugby to new markets but organisers of the southern hemisphere's elite club competition decided last month to kick them out after 2020, sparking concerns about the sport's growth prospects in Asia.
Mori previously served as JRFU chairperson for 10 years until 2015 when he was replaced by Masaru Okamura, former head of the Japan Chamber of Commerce. Mori had since served as honorary chairman.
Mori, who became prime minister in 2000 and retired from politics in 2012, has been heavily involved in promoting sports in Japan.