Like the other Numbers, Rokki is massive in size, being comparable to an ancient giant. He is bald but has a noticeable amount of body hair on his chest, arms, and legs, as well as stubble on his upper lip. His body is covered in tattoos, including a swirl-shaped design around his head, the daiji 陸 ("six") on his forehead, and a crown-like design on both of his arms. He possesses two dark-colored horns which point straight up. The only clothes he wears are a pair of dark-colored overalls which cover his abdomen but leave much of his upper chest exposed.
Rokki guards the gate to the armory on Onigashima, and seems to be diligent in this, as Yamato stated that she would likely have to fight him to get past him. However, Rokki was also shown to be asleep at the door, even as a war had broken out above him.
Like the other Numbers, he possesses a unique laugh based on his name: "Rorokiki" (ロロキキィ,"Rorokiki"?). When he was attacked by Fuga, he also made the sound "Rokya" (ロキャ,"Rokya"?).
Abilities and Powers
Rokki's abilities have not been shown, but given his nature as an artificial ancient giant, he is likely tremendously powerful.
Rokki possesses a morning star club, though has not yet been seen using it.
On the night of the Fire Festival, Rokki was stationed at the gate to the armory and fell asleep. However, he was unexpectedly attacked by fellow Number Fuga on Yamato's orders. Fuga's attack also broke open the gate, and Fuga held down Rokki while Yamato entered the armory.
Rokki's name contains the kanji for "six" (六,roku?) and the kanji for "oni" (鬼,"oni"?).
Rokki was the last Number to be introduced and named.