Just when Tokyo got a boost in its campaign to host the 2020 Olympics, a judo coach abuse scandal surfaced within the Japanese sporting culture and threatens to undermine the bid.

Tokyo bid officials were pleased on Jan. 30 when a poll showed public support had risen to 73 percent, given that low public enthusiasm helped derail the 2016 bid.

But the same day, the Japan Judo Federation revealed the head coach of the women's Olympic team, Ryuji Sonoda, had used violence against athletes at a training camp before the London Olympics. He resigned the next day.

The revelations raise concerns for Tokyo 2020 bid officials, knowing an IOC evaluation committee will visit in March. One of the main themes of Tokyo's bid is "athletes first."

On Friday, the Japanese Olympic Committee said a two-day preliminary hearing of its 31 Olympic sports federations found no cases of violence or harassment during training since the 2010 Vancouver Games.

Later Friday, the International Judo Federation issued a statement that members of the Japan women's judo team have been indefinitely suspended while an independent inquiry considers their complaints of ill treatment.

JOC secretary general Noriyuki Ichihara denied that officials were rushing investigations to wrap up the problem in time for the IOC evaluation visit to Tokyo.

"This is a huge problem for the entire sports community," Ichihara said at a news conference. "We are not rushing to deal with it just because the IOC is coming. This is going to take some time and patience."

Tokyo governor Naoki Inose has said he doesn't think the scandal will hurt Tokyo's bid. The JOC issued a statement saying it would conduct further investigations into the use of physical violence in judo and all sports, this time interviewing athletes.

The Japan Judo Federation revealed in last month that 15 female judoka sent a letter to the JOC at the end of 2012 saying they'd been subjected to harassment and physical violence by Sonoda at a pre-Olympic training camp. The federation, which knew about the problem since September when some of the women first raised the issue, still decided to renew Sonoda's contract.

Sonoda tried to justify his behavior by saying he was under tremendous pressure to produce gold-medal winners in London. He said he didn't think slapping was considered violence and he was trained the same way.

Sports minister Hakubun Shimomura has described the situation as the most serious crisis in Japan's sports history.

"The sports community must make concerted efforts to go back to the fundamental principle that violence should be eradicated from sports instruction," Shimomura said.

Days after Sonoda stepped down, two-time Olympic judo champion Masato Uchishiba was sentenced to five years in prison for raping a female member of a university judo club in 2011.

Naoki Ogi, a former teacher and popular social critic, attributes the corporal punishment to poor coaching techniques.

"Corporal punishment is an easy solution for instructors who lack leadership and skills, who know they won't be challenged," Ogi wrote on his blog. "It's a dirty trick."

Ogi suggests the JOC and the Japan Judo Federation coordinated their responses to the scandal.

"They must be colluding," said Ogi, adding the JOC should have launched its own investigation a long time ago. "There is no doubt this ongoing scandal will affect (Tokyo's) Olympic bid. It's a pity."

The complaints by the women were initially ignored by the judo federation, which has no women on its 26-member executive board, so they decided to take it to the JOC.

"We were deeply hurt both mentally and physically because of violence and harassment taken upon us by former coach Sonoda, in the name of guidance. It went far beyond what it should have," the women said in a joint statement released through their lawyers. "Our dignity as humans was disgraced, which caused some of us to cry, and others to wear out. We participated in matches and training as we were constantly intimidated by the presence of the coach while we were forced to see our teammates suffer."

Sonoda coached at the London Olympics, where Japan won one gold medal in women's judo. Many in Japan have pointed out that his actions go against the Olympic charter, which bans violence.

Former Yomiuri Giants pitcher Masumi Kuwata, once among the top pitchers in Japanese professional baseball, has spoken out against corporal punishment while revealing that he, too, was a victim of violence as a baseball player in elementary school.

"I don't think corporal punishment as a form of instruction makes one stronger," Kuwata said in an interview with NHK. "Those teaching sports need to change their methods to fit the times."

Judo holds a special place in Japanese society. Judo, which means "gentle way," was created in Japan and the first Japanese martial art to gain widespread international recognition. It became an official Olympic sport at the 1964 Tokyo Games.

The sport's founder, Jigoro Kano, considered judo the pursuit of self-defense, physical culture and moral behavior. The educator played a key role in making judo a part of the Japanese public school programs in the early 1900s. Women were banned from participating in matches until the 1970s and still face discrimination in promotions and ranks, former judo Olympian Noriko Mizoguchi said.

Author Robert Whiting, who detailed corporal punishment in Japanese baseball in his 1989 book "You Gotta Have Wa," said violence in Japanese sports traces its roots to martial arts.

"Corporal punishment is the legacy of the martial arts, where physical education means physical punishment and is considered a valid way of teaching," Whiting said. "Still evident all over Japan in all sports, it's very widespread. Screw up in practice and you get a slap on the head or a kick in the butt. That's how you learn."

When Sonoda resigned, the issue was in the spotlight following the suicide in December of a Japanese high school student who endured repeated beatings from his basketball coach. The student told his mother the day before he died that he had been struck 30 to 40 times by his coach.

The 47-year-old coach, whose name hasn't been disclosed, admitted slapping the teen when he made a mistake and said it was intended to "fire him up."

Corporal punishment at school is prohibited under Japan's Fundamental Law of Education, but some teachers still believe in the old ways.

According to the Education Ministry, about 400 corporal punishment cases are reported at public schools every year. In 2001, about one third of the cases resulted in injuries, mostly cuts and bruises to the head or the face. About a quarter of the school corporal punishment cases involve sports teams.

In 2009, a former sumo trainer was sentenced to six years in prison for his role in the fatal beating of a young wrestler during training. Former trainer Junichi Yamamoto ordered three wrestlers, in the name of instruction, to beat 17-year-old wrestler Tokitaizan, hitting him with beer bottles, a baseball bat and hosing him with cold water.

Despite the promises of reform, Whiting thinks the practices may be too entrenched in Japanese society for real change to occur anytime soon.

"What makes Japanese different from the United States is that generally Japanese coaches put themselves above the players, like a military drill sergeant," Whiting said. "Sports is much more militaristic in Japan. That's the legacy of the martial arts, where a whack on the head is considered a form of teaching."