Every sumo bout ends with a winner declared.
Even if the gyōji (referee) thinks both men crashed to the ground at the same instant, he is obliged to point his gunbai (war fan) toward either the west or east to signal that the wrestler from that side has won.
The five ringside judges, who are the ultimate authority, can overrule that decision if they believe the gyoji got it wrong. They may also call for a rematch if a clear winner is not obvious.
It’s been that way for almost 45 years.
Up to 1974, however, ties were a feature of sumo. Bouts could end without a winner being decided.
Not only that, but there were several different kinds of drawn contests.
Itamiwake, which hasn’t been seen since 1958, was a tie declared when one of the rikishi was too injured to participate in a rematch. Nowadays it’s an automatic loss if you are unable to fight.
Azukari was essentially a no-decision tie when the ending was too close to call.
It’s a result that hasn’t been seen since 1951. In the days when sumo was more about prestige and heated rivalries between various stables and groups, azukari was used to smooth over potentially contentious decisions that could have escalated into wider conflicts. The decision could only be made by the ringside judges.
Hikiwake was a drawn bout that occurred when a fight went on so long that both rikishi were completely exhausted and unable to keep going.
These days if a fight reaches that point a “water break” is declared. The referee carefully marks the position of the wrestlers and after a short break to catch their breath, they resume the fight from the same spot.
In the lower divisions, rematches are held instead of resumptions after the rikishi have been given two bouts to recover.