Sumo is a traditional combative Japanese sport that is well known throughout the world. Most rikishi (Sumo wrestlers) are professional competitors weighing 100 to 200 kg.
Rules are simple compared to western-style wrestling: two competitors wearing mawashi (silk belts) fight in a ring 4.5m in diameter and placed on a square mound. When any part of a competitor’s body, except the sole of the feet, touches the ground or goes out of the ring, he loses the bout.
The professional sumo tournaments take place six times a year for 15 days each in January, May and September at Ryogoku Kokugikan in Tokyo, March in Osaka, July in Nagoya and December in Fukuoka.
more info : http://www.sumo.or.jp/eng/
wikipedia
Sumo (相撲, sumō?) is a competitive contact sport where a wrestler (rikishi) attempts to force another wrestler out of a circular ring (dohyō) or to touch the ground with anything other than the soles of the feet. The sport originated in Japan, the only country where it is practiced professionally. It is generally considered to be a gendai budō (a modern Japanese martial art), though this definition is incorrect as the sport has a history spanning many centuries. Many ancient traditions have been preserved in sumo, and even today the sport includes many ritual elements, such as the use of salt purification, from the days when sumo was used in the Shinto religion. Life as a rikishi is highly regimented, with rules laid down by the Sumo Association. Most sumo wrestlers are very required to live in communal “sumo training stables” known in Japanese as heya where all aspects of their daily lives—from meals to their manner of dress—are dictated by strict tradition.
