Dohyo is a term used to refer to sumo rings made up of clay. Because bales filled with clay (dohyo) are used, they were originally called as dohyo-ba, dohyo being its abbreviated form.
For modern grand sumo tournaments, a square-shaped platform made of clay having a side of 6.7 m is first built, and a circle having a diameter of 4.55 m (15 shaku) is defined at the center by placing 16 bales (Shobu-dawara) on the platform. The east, west, south, and north edges of the circle each have a bale set slightly backward, which is called Toku-dawara. Twenty-eight bales (Kado-dawara) are placed in a square shape (seven bales for each side) to surround the circular Toku-dawara, and each corner of the square has a bale called Age-dawara. Total of 10 bales (Fumi-dawara) are placed as a step to climb up onto the dohyo (three bales for each of the east, west, and south sides and one for the north side), and total of four bales (Mizuoke-dawara) are placed at the south-west and south-east corners (two for each corner) to provide spaces for Mizuoke (water pail) in which Chikara-mizu (water offered to sumo wrestlers just prior to a bout) is kept. Therefore, total of 66 bales are used for one dohyo.
The bales are in large part made of knitted thin rice straw and filled with clay. When dohyo is built by local governments, strong sheets are sometimes used to make bales.
It is said that money has been buried in the dohyo. In fact, Kachiguri (dried chestnuts), dried kelp, rice, dried squids, and salt are buried in the dohyo as ritual gifts for gods.
Clay containing a small amount of bole is used as the clay for dohyo. This is because this type of clay is hard to break and resistant to vibrations after the building of dohyo. In addition, sand is scattered in the area inside the Shobu-dawara. This is also a safety measure to protect ankles of sumo wrestlers, for example. Furthermore, sand is scattered in a circular shape surrounding the Shobu-dawara. This is because it is easy to make judgment if the foot of sumo wrestlers has overstepped the shobu-dawara or not as their footprints are left. This sand is called as Janome.
Roof and tassel
Over the dohyo, hanging from the ceiling, is Hoya (roof). In the Meiji period, the style of Hoya was changed from Azumaya-zukuri to Sinmei-zukuri with gables having decoration of Chigi (forked finials) and Katsuogi (wooden billets placed atop and at right angle to a roof ridge). Four posts which supported the corners (the east, west, south, and north corners; more precisely, the east-north, east-south, west-south, and west-north corners) of the roof were omitted when a tournament was held with the Emperor in attendance in April 1931. Tassels hanging from the four corners of the roof are not merely tassels for decoration but they represent the cloths of the same color that once wrapped the omitted posts. These thick tassels are hanged instead of the posts. The four tassels represent four gods: the blue tassel (east), while tassel (west), red tassel (south), and purple or black tassel (north) represent Azure Dragon, White Tiger, Vermilion Bird, and Black Tortoise, respectively (the order may change depending on the region). These four tassels are made of twisted silk strings, and each of them is 2.3 m in length, 70 cm in thickness, and 25 kg in weight.
Small tassels called fusa are also hung from the central portion of the east, west, south, and north sides of the curtain (Mizuhiki-maku) on the hanging roof above the sumo ring.
Mizuoke and Shiobako (salt box) are replenished by Yobidashi (announcers who call sumo wrestlers to the dohyo before their bouts).
It is a water pail in which water called Chikara-mizu is kept, and Mizuoke has a hanger at its middle portion for hanging a towel.
It is 50 cm in both length and width and 40 cm in depth.
It is said that no dohyo was built for Sumai no sechie (the Imperial ceremony of Sumo wrestling) in ancient times. According to "Sumo-densho" (a manual on sumo wrestling written during the Edo period), it is said that audience defined a circular space having a diameter of seven to nine meters (four to five ken) and called it as Hito-hoya in the Kamakura period. This is the origin of dohyo. The history of the grand sumo tournaments started in the Edo period. Because in the case of 'hitokataya' (sumo arena made by crowd of people), audience could interfere sumo bouts to help their favorite wrestlers, resulting in frequent occurrence of quarrels among the audience, the fighting area was surrounded by four posts and ropes, as in the ring of wrestling, in the Kanbun era (1661 to 1673). The area surrounded by the posts and ropes changed into a square dohyo surrounded by bales. These square dohyo can be found even now at shrines in various regions and also in Nanbu-zumo, and they are still actively used. Then, a circular dohyo having a diameter of 3.94 m (13 shaku) defined by Goto-dawara (large bales) was built in the Enho era (1673 to 1681) with a hoya having an Azumaya-zukuri style roof and four posts wrapped with cloths of four colors representing the four gods. In the Kyoho era (1716 to 1736), the bales were reduced by half in size and the lower half portions of the bales were buried underground, resulting in a ichiju-dohyo (single circular dohyo). Another circular arrangement of bales was added to surround the ichiju-dohyo resulting in a niju-dohyo (double circular dohyo), which is also called Janome dohyo. This type of dohyo was called sanju-roppyo (literally 36 bales) because the inner circle includes 16 bales and the outer circle includes 20 bales.
On June 11, 1791, Oikaze YOSHIDA of the YOSHIDA-TSUKASA family built a dohyo overnight for a Joran sumo tournament (a tournament held with the Shogun in attendance) scheduled to be held on the next day for the 11th Shogun Ienari TOKUGAWA and conducted the first Hoya-biraki ceremony (a ceremony to celebrate building of a new hoya). The style of the hoya roof changed to the Sinmei-zukuri in the Meiji period.
When radio broadcasting of the grand sumo tournaments was started by NHK in January 12, 1928, Sikiri-sen (starting lines) was added to the dohyo to cause the bouts to be completed within the broadcasting time. In March, 1930, positions of ringside sumo judges, who were sitting on the dohyo until that time, were moved to places below the dohyo because their presence on the dohyo might not only block sight lines of the audience but also become a cause for injury of sumo wrestlers, and the number of judges was increased to five and the Shiooke (salt pails) were tied to the hoya posts. In the grand sumo tournament held with the Emperor in attendance in April, 1931, the inner circle of the niju-dohyo was omitted, changing the diameter to 4.55 m (15 shaku). The posts of hoya were also omitted and the style of the hanging roof was changed to the Shinmei-zukuri. In September, 1945, the diameter of the dohyo was changed to 4.84m (16 shaku). However, this change was cancelled after the tournament held in November 1945 due to objections from the association of sumo wrestlers, and the dohyo having a diameter of 4.55 m has been used since then. The roof hanging from the ceiling was first adopted when the Kuramae Sumo amphitheater was opened.
It is said that because there are gods of Shinto in the dohyo, sumo wrestlers clap their hands in prayer before their bouts. They clap their hands based on the approval from the YOSHIDA-TSUKASA family, the head family of sumo.
Noble priests of Izumo Grand Shrine, together with related people such as high-ranking staff of the Japan Sumo Association, high-ranking staff of the department of judging of the association, and people from sumo tea shops, conduct Shinto rituals at Nominosukune-jinja Shrine (Sumida Ward, Tokyo) two days before a grand sumo tournament held at Tokyo-Ryogoku Sumo amphitheater.
In addition, a dohyo ceremony is held one day before each grand sumo tournament. For the dohyo ceremony, three sumo gods (Takemikazuchi and other two gods) and seven Heisoku (offerings of rope, paper etc.) are decorated at the center of the dohyo, together with rice wine, rice, salt, etc. The host of the ceremony, who is Tate-gyoji (one of the two highest ranked referees) conducts the Shinto rituals and declares the opening of hoya with a gunbai uchiwa (war fan) in his hand while gyoji helping the Tate-gyoji sings Seibatsu no norito (a Shinto prayer for purifying). Then, several yobidashi walk around the dohyo three times as Kiyome no taiko. This ceremony was first conducted as Hoya-biraki when Oikaze YOSHIDA built the dohyo one day before the Joran sumo tournament for the 11th Shogun Ienari TOKUGAWA in June 11, 1791.
Dohyo-iri (Ring-entering ceremony) now performed by Yokozuna (sumo wrestler of the highest rank) has the same meaning as that of Jichinsai (a ceremony performed before the groundbreaking of a new building) in that the Yokozuna stamps on the ground symbolically driving evil from the dohyo.
In this manner, it is said that the dohyo is a sacred area, and women are not allowed to enter. Although this custom is gradually disappearing and more and more women and children are allowed to enter the dohyo, it still can cause problems at highly official and formal occasions. In 1989, although chief cabinet secretary Mayumi MORIYAMA expressed her intention to present the prime minister's cup on behalf of the prime minister on the dohyo, the Japan Sumo Association rejected her proposal, causing fierce debate on discrimination against women. In addition, when governor of Osaka Prefecture Fusae OTA expressed her intention to present the governor's cup on the dohyo, her proposal was again rejected by the Japan Sumo Association.
On the 11th day of the September grand sumo tournament in 2007 (September 19, 2007), a happening occurred in which a woman having throwaways in her hand tried to climb up onto the dohyo and was arrested by Nishikido oyakata (a mater of sumo-beya), Takamisakari (a sumo wrestler), etc.
It is to be noted that onna-zumo (women sumo) tournaments used to be held in a dedicated dohyo.
On the fourth day of the January grand sumo tournament in 1998, during a Makushita (the third highest division in sumo) bout between Otakayama and Yachi, when Yachi's shoulder hit the dohyo, a large hole appeared with a collapsing sound in one corner of the dohyo under the black tassel. On that day, the clay of the dohyo was rather dry and many cracks were found on the surface of the dohyo. It seems that the impact given by Yachi's shoulder caused a weakened portion inside the dohyo to collapse to create the large hole. Fortunately, the damage of the dohyo due to the hole was not serious and following Makushita and Juryo (the second highest division in sumo) bouts were held as scheduled. The dohyo was tentatively repaired by Yobidashi hitting it with beer bottles before the Makunouchi (the top division in sumo) bouts.