Japan will pick its marathon team for Tokyo 2020 through the newly-launched Grand Champion Series ©Getty Images

Marathon runners wanting to represent Japan at the 2020 Olympics in Tokyo will have to take part in a special two-year challenge series.

The Grand Champion Series has been launched by the Japan Association of Athletics Federations (JAAF) following an extraordinary meeting. 

The series of races is due to start this summer and take place until the spring of 2019, the JAAF said. 

Runners with the best times and places will qualify for the series finale, the Grand Champion Race, to be held on the same course as the Olympic marathon sometime after September 2019.

The top two men and women each in the Grand Champion Race will qualify automatically for Tokyo 2020. 

Runners who finish in the top eight at this summer’s International Association of Athletics Federations World Athletics Championships in London or win a medal at next year’s Asian Games in Jakarta will also be eligible to run in the Grand Champion Race.

At last year's Olympic Games in Rio de Janeiro, the highest placed Japanese runners in the marathon were Satoru Sasaki, 13th in the men's race, and Kayoko Fukushi, 14th in the women's.

Japan's Mizuki Noguchi won the women's Olympic marathon at Athens 2004 ©Getty Images
Japan's Mizuki Noguchi won the women's Olympic marathon at Athens 2004 ©Getty Images

"Two qualify automatically [for Tokyo 2020] so the selection process is crystal clear," JAAF general secretary Mitsugi Ogata told Japanese agency Kyodo News. 

The remaining berth in the men and women's teams will be awarded to the runners with the fastest time from three races held between the autumn of 2019 and spring of 2020 called the Grand Champion Final Challenge.

The marathon is an obsession in Japan and among the most coveted of Olympic medals.

Japanese women won consecutive Olympic gold medals thanks to Naoko Takahashi at Sydney 2000 and Mizuki Noguchi at Athens 2004.

The only man to win an Olympic gold medal in the marathon is Son Kitei at Berlin 1936.

He was a Korean forced to represent Japan as his country was occupied at the time.

The record books were later amended to show his Korean name Sohn Kee-chung.

Nan Shoryu, another Korean forced to run for Japan, won a bronze medal in the same race. 

Kenji Kimihara and Koichi Morishita won silver medals in the marathon at Mexico City 1968 and Barcelona 1992.

Sohn Kee-chung won the Olympic marathon in Berlin 1936 under the name Son Kitei, which he was forced to adopt because Korea was occupied by Japan at the time ©Getty Images
Sohn Kee-chung won the Olympic marathon in Berlin 1936 under the name Son Kitei, which he was forced to adopt because Korea was occupied by Japan at the time ©Getty Images

Kokichi Tsuburaya won a bronze medal the last time Tokyo hosted the Olympics, in 1964, 

He was second entering the Olympic Stadium but was passed by Britain's Basil Heatley in the final few metres. 

Afterwards, Tsuburaya claimed he had "committed an inexcusable blunder in front of the Japanese people".

In 1968, he committed suicide by slashing his wrist in his dormitory room where had had been preparing for the Olympics in Mexico City.