Sumo (相撲, sumō) is a Japanese full-contact sport.
In sumo, a wrestler (rikishi) attempts to force another wrestler out of a circular ring (dohyō) 4.55 metres in diameter. Also, the rikishi try to use their skill to force an opponent to touch the ground with anything other than the soles of his feet.
Sumo tournaments (basho) take place in Tokyo, Osaka, Nagoya and Fukuoka. There are a total of 6 major professional tournaments (known as honbasho) per year, in January, March, May, July, September and November.
A tournament normally lasts for 15 days and features matches from different divisions. The top 5 ranks are known as the "Top division", also called the Makuuchi (幕内) or Makunouchi (幕の内). It is fixed in size and always contains 42 rikishi.
The ranks included in the top division are yokozuna, ozeki, sekiwake, komusubi and maegashira.