A traditional Japanese form of wrestling in which a bout is won by forcing the opponent out of a clay ring called a dohyo, about 4.55 meters across, or by making them touch the ground.
Sumo's top referees, tate-gyōji, wear a short dagger in their sash, symbolizing readiness to die over a bad call. No one commits seppuku today, but after an overturned ruling the referee still offers to resign; the sumo association customarily refuses.