Drawn from ancient samurai traditions, judo has traditionally been dominated by the Japanese, though its prevalence has slipped in recent years.
After winning just one gold medal in the judo competition last week, some declared it the demise of Japanese judo.
"The supremacy of Japanese judo has come to an end," said French judoka Lucie Decosse, a gold medallist and triple world champion.
"Many other countries have suffered in the past because of Japanese supremacy," she said. "The fact that Japan is not doing very well, we have to take advantage of it."
Japan was devastated after it won only four gold medals at the Beijing Olympics, half of what they took home from Athens. Heading into the Olympics with a largely new team, experts predicted they would win at least six to eight gold medals.
Judo's governing body even changed the rules after Beijing to rule out grappling techniques often used by Europeans and North Americans. The changes forced competitors to use more classic Japanese judo, such as throws from an upright position rather than the groundwork that many eastern Europeans excel at.
"Theoretically, the rule changes favour the Japanese," said Ray Stevens, a British silver medallist from the Barcelona Olympics. "But very good players will always adapt so there's no guarantee for the Japanese," he said.
There wasn't. Only Kaori Matsumoto was able to win a gold in the women's 57-kilogram division, with the Japanese men completely shut out. It was the first time since judo was introduced as an Olympic sport in 1964 that the Japanese men have not won gold.
Sitting atop the judo medals table was Russia, with three golds. France and South Korea both won two golds, followed by one each for Japan and Cuba.
Even the Japanese judo players were at a loss to explain their abysmal performance.
"We are the ones who give the impression that Japanese judo has declined," said Masashi Nishiyama, a bronze medallist. "This is the reality and I am very disappointed about that."
Mika Sugimoto, who won Japan's last judo medal — a silver in the women's heavyweight division — was also baffled by their poor performance. "I am quite confident we have practiced more than other countries," she said.
"I really don't know why we couldn't get more medals," she added, saying it was "regrettable" she had to settle for silver.
Men's coach Shinichi Shinohara said the team had struggled to find athletes who could replace Japan's previous judo stars. "I am very sorry," he said of the team's failure.
U.S. judo coach Jimmy Pedro said the Japanese team, comprised mostly of Olympic novices, had simply overtrained in the lead-up to the games. "They've competed at too many competitions and now they're flat," he said.
But not everyone was convinced it was all over for Japan. American gold medallist Kayla Harrison said the pressure of the Olympics might have gotten to the Japanese judo fighters.
"They are still fierce competitors," she said. "But a lot of them were the number one and number two in their category and came into this with a huge target on their back," she said. "Sometimes having that doesn't work in your favour."
Kozue Suzuki, a reporter at Japanese daily Asashi Shimbun, said Japanese back home were shocked and disappointed by the judo team's performance.
"People in Japan say silver and bronze are not medals and that gold is the only medal," she said. "But unfortunately this time there are not very many at all."
Judo's biggest star — newly crowned Olympic champion Teddy Riner — has no doubt Japan will redouble its judo efforts. The five-time world champion said he didn't have any advice for the Japanese but wasn't sure they needed it.
"This week, they lost it," Riner said. "But they have super judoka and I am sure we will see the Japanese be a threat at future competitions."