In professional sumo, the ringside judges are called shimpan.
Five shimpan usually sit around the dohyo during a top-level bout. They watch the action from different angles and can intervene when the referee’s decision is unclear or disputed. A judge may call for a mono-ii, a conference to review the finish with the other judges and the referee.
After discussion, the judges can confirm the referee’s decision, overturn it, or order a torinaoshi, meaning a rematch. They may also determine that the referee should make a different ruling when a wrestler stepped out or touched the ground first.
Shimpan are retired professional wrestlers who serve as elders of the Japan Sumo Association. Their experience helps them assess highly rapid movements that may be difficult to judge from one viewpoint. The shimpan system is therefore a formal part of sumo officiating, not an informal consultation.