Executes the rule violators of the tournament. He is a 195cm tall blond man who fights with metal knuckle claws. He wears a bright red hooded jacket that is open at the front, exposing most of his tattoo-covered torso. Gunji is not very smart and acts spontaneously and violently, and is extremely sadistic in his killings, but still has a fun-loving, childish innocence to him. Gunji has an affinity with name calling. He is usually seen with Kiriwar, who he calls "jijii" ("old man"), calls Arbitro "papa", and Shiki "Shikitty". Gunji seems to confuse cats with dogs, since although Kau is supposed to be a pet "dog", Gunji refers to him as 'Tama', which is a common pet name for a cat. In the manga, he also names a cat that he finds 'Pochi', the common pet name for a dog.

Also, though many English-speaking fans spell and pronounce his name as "Gunzi," the pronunciation of "Gunji" is more correct as "zi" does not exist in the Japanese alphabet and as it is spelled "Gunji" on official merchandise.