Judo became an Olympic sport in the 1964 Tokyo Games and was dominated by the country of its origin until the 2008 Games in Beijing.
This summer in London, Japan's men failed to win a single gold medal in judo and its women claimed just one. It was the first time since judo's Olympic debut that the men failed to grab gold.
Have Japan's judoka become weaker or have those in other countries gotten stronger? Here are some questions and answers:
What is the origin of judo?
Jigoro Kano opened a dojo in Tokyo in 1882 to teach a style of jujitsu he later called judo, according to the Japanese Olympic Committee.
Kano was deemed the originator of judo. The International Judo Federation, which was founded in 1951 and based in Budapest. Kano also was the first Asian member of the International Olympic Committee, according to the IJF. The All Japan Judo Federation was founded in 1949.
How strong was Japan in Olympic judo?
From the Tokyo Games until Beijing, Japanese judoka won 35 gold medals. France, its nearest rival during that time, bagged 10, according to the IOC.
The 2004 Athens Games saw Japan collect its highest single gold medal haul, winning eight.
How did Japan's judoka fare in London compared with other judoka?
In terms of gold medals, Japan and six other countries tied for fourth place with one each. Russia took three golds and France and South Korea won two each.
In terms of all medals combined, Japan and France shared the lead with seven, followed by Russia with five.
Why did Japan get only one gold in London?
Experts point to the internationalization of judo and the rise of strong foreign contenders.
Yasushi Oishi, 69, a coach at the Oishi Dojo in Obu, Aichi Prefecture, where several Olympians train, said judo has become especially popular in France.
"France has been very open to judo and lots of Japanese judoka went to coach there. Now judo is popular as a sport and parents want their children to learn it because of its focus on strict sportsmanship and discipline," Oishi told The Japan Times.
Also, France has lured talented judo coaches by offering them stable positions as government workers despite their lack of French citizenship, he said.
"It's very good for us that judo has become a globally recognized sport," he said.
Oishi also noted that Japanese judoka outnumber their foreign counterparts by a great deal, which in many cases means their foreign counterparts receive more attention in a more devoted training environment that receives nationwide support over the four-year runup to the games.
Does Japan hold high expectations for Olympic judo?
Yes. From Barcelona to Beijing, judo accounted for 56 percent of Japan's gold medals and 37 percent of all its medals combined.
In London alone, the one judo gold accounted for 14 percent of the seven Japanese golds and 18 percent of the 38 medals Japan won overall.
"In the future, it will be difficult for Japan to get so many medals in judo," Oishi said. "We should not place too much pressure on Japanese judoka. Japanese judo has not gotten weak; other countries have become stronger."
Who has won the most Olympic gold medals in judo so far?
Tadahiro Nomura won three gold medals, one each in Atlanta, Sydney and Athens. Nobody else has won as many golds in Olympic judo, according to IOC statistics.
Hitoshi Saito won two golds, one in Los Angeles and the other in Seoul, and Ryoko Tani did likewise in Sydney and Athens.
Likewise, Austrian Peter Seisenbacher took golds in Los Angeles and Seoul, while Poland's Waldermar Legien did the same in Seoul and Barcelona. Frenchman David Douillet got one gold in Atlanta and another in Sydney, and Dongmei Xian of China took the center podium once in Athens and once in Beijing, according to the IOC data.
Dutchman Willem Ruska won two gold medals in Munich, in the 93-kg class and in the open category, which was eliminated in 1988. The heaviest category in judo now is the +100kg class.