Sumo Wrestling the name has come about from sumo from the word Sechie-zumo which was performed at the Japanese imperial court as a combined religious function and entertainment. A Rakishi is a registered sumo wrestler meaning "a gentleman of strength".  Sumo found its rules to become a sport. Developed from sumo were other forms of fighting such as jujitsu which was practiced by the samurai. Six major tournaments over four cities three held in Tokyo, and one each in Fukuoka, Nagoya and Osaka are held yearly. The sumo ring is called the dohyo and it is approx. 18 feet square and is constructed of clay. The hard surface is covered with a thin layer of sand with straw roped markings buried  The bout ring is a circle approx. 15 feet in diameter the dohyo has a roof to represent a Shinto shrine. A sumo match is won by pushing the appointment out of the ring or making him touch the straw markings. Boxing and striking of opponents result in disqualification as well as to grab removing the belt of cloth covering themselves. The wrestler who either first touches the ground or leaves the ring before his opponent, loses. The fights themselves usually last only a few seconds. There are no weight classes all wrestlers that compete could find themselves up against others twice their size. Sumo wrestlers are known to be some of the biggest men in the world working out and eating huge amounts of food and sleeping a lot to gain mass. The best wrestlers are in their prime around the age of thirty. Wrestlers live in stables and live on rich diets living with the Toshiyori  the retired rikishi who remain in ozumo as managerial employees of the Nihon Sumo Kyoka the official sumo league also known as oyakata they train and educate the rikishi living with them to be their mentors. Some of the top japanese restaurants will serve sumo style dinners for people that want to sample some of the traditional sumo cooking and recipes.