A Gunbai (軍配; Literally meaning "army arrangement") or gunbai uchiwa (軍配団扇; Literally meaning "army arrangement fan") is a non-folding fan, usually made of wood. It was used in ancient Japan by samurai officers to communicate with their troops. Nowadays, it is used by referees of professional sumō matches.
Madara Uchiha during his lifetime was famed for the use of this fan in battle. Obito Uchiha would later wield this fan while posing as the legendary Uchiha, before returning it to his reincarnated ancestor during the Fourth Shinobi World War. It is a wide fan with tomoe on it and has a long handle with bandages wrapped around the base, as well as having a long chain attached to it. In the past, when Madara used it, it was brown with a black border, with red tomoe, and a chain was attached to the handle that appears to have been connected to his kama. When Obito started using it, it was depicted as having a purple tint with a black border, and tomoe design on it, with the chain appearing to enter his sleeve. During the Third Shinobi World War it was seen hanging on a wall inside the caverns of the Mountains' Graveyard.
Obito wielded the gunbai predominantly like a flail using the chain attached to guide the fan which he can use also as a shield because of its durability, as it was able to block Naruto's Super Mini-Tailed Beast Ball without receiving any noticeable damage. Madara also wielded it, both as a shield and as a flail in conjunction with his kama, and it also allowed him to perform various techniques.