J-Keeper

A manga-only character, J-Keeper is a gigantic armored warrior initially believed to be a member of the Jyūshinshu who fights with a giant mace-halbard(which he calls Hisatsu Kōken). He killed Magensha on orders from Kurei, and later attacked Koganei and Saicho. When Joker intervened, he suggested a team-up only to betray and critically injure Saicho. Joker then easily stopped one of J-Keeper's attacks and cut him to pieces, saying J-Keeper is nothing more than a placeholder for the real member of the Jyūshinshu: Joker himself. 

Source: http://flameofrecca.wikia.com/wiki/J-Keeper