Sumo: Japanese Wrestling

Sumo (相撲) is a Japanese style of wrestling and Japan's national sport. It originated in ancient times associated with Shinto ritual, and even certain shrines carry out forms of ritual dance where a human is said to wrestle with a kami (a Shinto divine spirit). Many rituals with religious background are still followed today. 

The basic rules of sumo are simple: the wrestler (Rikishi) who first touches the ground with anything besides the soles of his feet, or who leaves the ring before his opponent, loses. Fights take place on an elevated ring, called a "dohyo (土俵)", which is made of clay and covered in a layer of sand with 4.55 metres (14.9 ft) in diameter and 16.26 square metres (175.0 sq ft) in area. The fights themselves usually last only a few seconds, or in rare cases, about a minute. 

There are six divisions in sumo: makuuchi (maximum 42 wrestlers), jūryō (fixed at 28 wrestlers), makushita (fixed at 120 wrestlers), sandanme (fixed at 200 wrestlers), jonidan (approximately 185 wrestlers), and jonokuchi (approximately 40 wrestlers). Wrestlers enter sumo in the lowest jonokuchi division and, ability permitting, work their way up to the top division. The topmost makuuchi division receives the most attention from fans and has the most complex hierarchy. The majority of wrestlers are maegashira and are numbered from one (at the top) down to about sixteen or seventeen. Above the maegashira are the three champion or titleholder ranks, called the sanyaku, which are not numbered. These are, in ascending order, komusubi, sekiwake, and ōzeki.

At the top of the Rikishi hierarchy stand the yokozuna (grand champion). Once a wrestler reaches the rank of yokozuna, he cannot lose this status but he will be expected to retire when his results begin to worsen. Many former Rikishi remain active in the sumo world as members of the Japan Sumo Association.

Kokugikan, the sumo stadium in Tokyo Ryogoku

Most elite wrestlers are highly trained athletes between 20 and 35 years old. They typically live together in residential and training complexes, called "stables", where all aspects of life, from sleeping and eating to training and free time, are strictly regimented by the coach, called the "stable master".

There are no weight restrictions or classes in sumo, meaning that wrestlers can easily find themselves matched off against someone many times their size. As a result, weight gain is an essential part of sumo training. The typical sumo dish, chanko nabe, is a hearty stew full of vegetables, meat and fish. 

Six tournaments are held every year, each one lasting 15 days. Three of the tournaments are held in Tokyo (January, May, September), and one each in Osaka (March), Nagoya (July) and Fukuoka (November).