noun
head referee (sumo)
The highest-ranking referee in professional sumo, distinguished by wearing a dagger (tantō) as a symbol of the seriousness of their decisions.
立行司は土俵上で短刀を差している。
The head referee wears a dagger on the sumo ring.
立行司の判定に物言いがついた。
The head referee's decision was challenged.
A general sumo referee; 立行司 is the highest rank among them.
From 立て (tate, 'leading') + 行司 (gyōji, 'sumo referee'). The exact historical origin of the rank is uncertain.