Neiji Rockheart (ネイジ・ロックハート) was the strongest individual on the Gladiator Island.
Neiji is a large and muscular man.
Currently, Neiji's name and memories have been eaten by Louis Arneb, erasing his existence from the world and putting him in suspended animation.
During the attack on the Pleiades Watchtower, which was being lead by the Sin Archbishops of Gluttony, Emilia succesfully knocked Ley Batenkaitos down with an Ice Hammer. After a few minutes, Ley transformed into the body of Neiji Rockheart. Despite Ley transforming into him, it was Louis who controlled the body.
Great Power: Neiji is mentioned to be one of the strongest individuals on the Gladiator Island. There was no army around that was able to fight him.
Fist King's Palm: Neiji is able to strike his opponent with an extremely powerful internal attack. During the incident at Priestella, Ley employed this techinque against Ton, despite "Ryuuhou" being active which resulted into him puking and crumble to the ground. Roy Alphard also performed this against Julius to shatter his sword..