Sumo bouts are conducted in a ring with a hard dirt surface. On top of a square platform, there is a circular ring 4.55 meters (about 15 feet) in diameter. The bouts take place inside the ring.
Throwing salt into the ring (Japan Sumo Association)
After their shikona (official wrestling names) are called, the wrestlers climb into the ring, ritually stamp their feet on the ground, and throw purifying salt into the ring. They then match their opponent's movements as they lower their waist, open their knees to the side, and go into their shikiri (taking their mark and facing their opponent in a posture that will allow them to move forward at any moment). The wrestlers match their breaths with their opponent, and once both of them place a fist on the ground, the match begins. While the bout is underway, the referee shouts "Nokotta!" (Remaining!) while the wrestlers are grappling with each other and "Hakkiyoi!" (Come on!) when the wrestlers are not moving.
Illustrations 1 and 9 are from ILLUSTRATED MARTIAL ARTS & SPORTS IN JAPAN, published by JTB Publishing, Inc.
2 and 5 are from Sumo Daijiten (Sumo Encyclopedia), published by Gendai Shokan.
3, 4, 6, 7, and 8 are from Encyclopedia Nipponica, published by Shogakukan (illustrator: Tanaka Yoshiyasu)
When one of the wrestlers is forced out of the ring or touches the ground with any part of his body other than his feet, the referee raises the fan in his hand to declare the winner. The way the winning wrestler achieves victory is called the kimarite. Forcing an opponent out of the ring by getting in close and lifting him out by his mawashi is called yorikiri, for example, while bringing him down is known as yoritaoshi. When a wrestler uses his weight to push his opponent backwards down to the ground, this is called abisetaoshi.
It is called oshidashi when one wrestler pushes the other underneath his arms or in the chest and forces him out of the ring. And whether it is in the ring or outside of it, oshitaoshi is a move by which a wrestler pushes his opponent to the ground. When a wrestler uses one arm to grab his opponent underneath the arm or on his side and forces him down at an angle, this is called tsukiotoshi.
It is known as uwatenage when a wrestler grabs his opponent's mawashi from outside the opponent's arms and throws him to the ground, and when he does the same thing and drags his opponent, it is called uwatedashinage. When a wrestler grabs his opponent inside his arms, this is shitatenage. The number of legal moves has increased and decreased over the years, but at present there are 82.
In addition, there are 8 moves that are prohibited, including striking an opponent with a clenched fist; poking an opponent in a vulnerable area, such as the eyes and the stomach; and kicking an opponent in the chest or the stomach. A wrestler who uses any of these moves loses the match by default.