In sumo, a is the loincloth that (sumo wrestlers) wear during training or in competition. Upper ranked professional wrestlers wear a as part of the ring entry ceremony or .
Mawashi
150px|thumb|right|[[Hakuhō Shō in a silk , worn by during tournaments. Colour matching sagari strings hang from the mawashi across his legs.]]
Sekitori
During competition
For top ranked professional (known as ), the mawashi is made of silk and comes in a variety of colours. It is approximately in length when unwrapped, about wide and weighs about . It is wrapped several times around the and fastened in the back by a large knot. A series of stiffened silk fronds of matching colour called are inserted into the front of the . Their number varies from 13 to 25, and is always an odd number. They mark out the only part of the that it is illegal to grab on to: the vertical part covering the 's groin, and if the sagari fall out during competition the (referee) throws them from the ring at the first opportunity.
Many are superstitious and change the color of their to change their luck. Sometimes a poor performance causes them to change colors for the next tournament, or even during a tournament, to improve their luck. Ōnoshō did this during the 2020 July tournament, when, after several losses in a row, he changed from crimson to dark gray.
thumb|left| in white cotton training .
During training
only wear the silk during competitive bouts either during ranking tournaments or touring displays. During training, wrestlers wear a heavy white cotton . Senior in the top two divisions wear a white mashi with one end distinctively looped at the front. Wrestlers do not wear a during training.
Lower-division rikishi
ranked in the lower professional divisions wear a black cotton both for training and in competition. In competition, cotton are inserted into the belt, but these are not stiffened.
Amateur sumo
Amateur sumo wrestlers wear a cotton of any color without the looping accorded to the senior professional's training garb. Additionally, they may wear a tag on the front of their that identifies them individually or the nation they are competing for, depending on the competition. Amateur sumo wrestlers are also allowed (or required, in the case of women wrestlers) to wear shorts or leotards under their while professional are not.
Techniques and rules
Sometimes a may wear his in such a way as to give him some advantage over his opponent. He may wear it loosely to make it more difficult for an opponent to throw him, or may wrap it tightly and splash a little water on it to help prevent his opponent from getting a good grip on it. His choice depends on the techniques he employs in his bouts. Thus a wrestler who prefers belt sumo usually wears it more loosely, while one who prefers pushing techniques tend to wear the more tightly.
If a wrestler's comes off during a tournament bout, he is automatically disqualified. This is extremely rare, but did occur in May 2000, when wrestler Asanokiri's came off during a match with Chiyohakuhō. However, for most of sumo's history, whether or not a wrestler's came off during a bout was considered irrelevant, and the policy of disqualification only came into place when Japan began adopting European attitudes towards nudity.
The may advertise the produce of a sponsor of the (for example Bulgarian Kotoōshū was sponsored by a Japanese brand of yogurt, Bulgaria, which was prominently displayed on the front of his ) or be a gift from one of the 's support groups. Alternatively, some foreign-born (such as Czech-born Takanoyama) bear their national flag on their . Popular may be given many of these .