The various implements used by samurai commanders to signal orders on the batter field or to direct troop movements were referred to as jineigu. Among them, the gunbai uchiwa - or gunbai - was a type of fixed fan used by generals and daimyō to signal orders during battles. It was frequently decorated with a large red sun in the center, but some were also adorned with moon or planets designs as well as with kanji or bonji characters. During the Edo period, the gunbai came to be viewed as a symbol of power and status, as only high-ranking samurai would carry one during public ceremonies and parades.
Gunbai uchiwa were typically made from materials such as leather or wood, but in the early Edo period, swordsmiths from the Hidari Mutsu school in Settsu province (Osaka) produced a number of them made entirely of iron. These have a sharp, geometric shape, as opposed to the typical rounded form, and could be used as weapons. During the Edo Period, in fact, there were numerous situations in which a samurai would be unable to use his sword. For example, when visiting another person's home, particularly that of a superior, a warrior was generally required to leave one or both swords with an attendant at the door.
Nowaday, gunbai uchiwa are used by sumo referee to give orders during tournaments.