In Japan, they have to be careful when they shout, "Kill the ref." He just might kill himself.

In case he makes a really bad call, 5-foot-1, 105-pound sumo referee Shonosuke Kimura carries a dagger whenever he climbs into the ring. The dagger isn't for defending himself against irate losers. It is for atonement in the extreme -- ritual suicide.

"It's a symbol of our heavy responsibility. If a referee makes a misjudgment, he should be prepared to commit hara-kiri," said Kimura. "Of course, we couldn't actually do that. We wouldn't have enough referees left alive for the sport."

Despite his diminutive build in a sport synonymous with heft, Kimura, 63, rules the sumo ring as its top-ranked referee.

Sumo matches often last only a few seconds, and it is not uncommon for both wrestlers to tumble out of the ring together. It is the referee's job to judge who fell first. A wrestler loses if he goes out of the ring or touches the dirt in the ring with any part of his body except his feet.

Referees work in flowing, traditional Japanese kimonos -- hardly the best attire for quick movement.

Five judges are at ringside to decide any questioned matches with the help of video replays. According to the Japan Sumo Association, Kimura has had only one decision overturned in three years as top referee. He was so embarrassed he offered to resign -- but the dagger stayed sheathed.