A Japanese high school girl who violated a rule banning females from being on a baseball field where boys are playing or practising has sparked debate in the country.

Momona Shuto, a third-year student at Oita High School in southwestern Japan and an assistant for its baseball team, was helping during a team practice session at Koshien Stadium in preparation for Japan's annual summer tournament, which starts on Sunday.

Wearing a team uniform, she had been throwing balls and assisting the team with batting practice - all part of her normal job - when she was ordered off the field by tournament officials earlier this week.

The school team's manager subsequently issued an apology, but the Japan High School Baseball Federation, which organises the tournament and sets the rules, defended its position, saying the ban was purely for safety reasons.


"We have a rule that only boys play in games, which means those players are aware of the risk of injuries," federation director Masahiko Takenaka told AFP on Friday.

"When girls are not supposed to play among males, we cannot possibly allow a situation where they get hurt," he added.

The annual 15-day men's tournament held at the stadium every year in the city of Nishinomiya is a key part of summer in baseball-mad Japan and many of the youth stars go on to storied careers in both Japanese and US professional leagues.

Hidemasa Hori, who directs the separate High School Girl's Baseball Tournament, said girls are more than up to the task of playing and assisting.

"I have never felt it is so dangerous for girls to play baseball," he told AFP.

"Girls also work hard to reach Koshien," he said, referring to team assistants like Shuto.

"I think it is such an outdated idea to ban only girls."

Others took to social media to voice their anger over the incident.

"This is outright discrimination," said one Twitter user. "Poor girl."

"What a punishment, when we have a female professional baseball league," said another.

But Takenaka denied that the rule was based on misogyny, which is often a point of criticism in Japan's national sport of sumo.

Sumo dohyo, or rings, under the Japan Sumo Association are seen as a sacred places rooted in the indigenous Shinto faith and women are barred from stepping in.

The association's rituals strictly forbid any contact with blood, such as that shed by women during menstruation and childbirth.

"As far as the baseball games that the federation oversees, girls are allowed on the bench to keep records and to go onto the field before and after a game," Takenaka said.

"They are not completely banned from the field."