Sumo wrestling is a contact sport that originated in Japan, this the only country where it is practice professionally, it is viewed as a modern martial art. The wrestlers attempt to force another wrestler out of a circular ring (dohyo) or to touch the ground with any part of the body other than the sole of the feet. The wrestler mostly live in communal settings known in Japanese as the Heya where all aspect of there daily live from meals to dressing are dictated by strict tradition.

Sumo is Competitive contact sport. A match is played between two players, designated East and West. They make the best possible use of the 4.55 diameter dohyo and fight, almost naked, using they full strength. Competitions are open to men and women, however, no contest between a man and a woman is allowed.

Women weight categories
 Light-weight under 65 Kg
 Middle-weight under 80 Kg
 Heavy-weight above 80 Kg
 Open-weight
Men weight categories
 Light-weight under 85 Kg
 Middle-weight under 115 Kg
 Heavy-weight above 115 Kg
 Open-weight