User blog comment:FairyRaven/Fairy Tail Chapter 391: Gray vs. Silver, Review and Commentary/@comment-7418318-20140704102219/@comment-25111584-20140704113354

... Make way for Zaraki Kenpachi of FT, Deliora! Maybe he just killed his predecessor, which is how he showed his strength to Mard. After all, he's a Devil Slayer and Keith implies that he can keep the other Demon Gates in check, so I don't think it'd be that difficult for him to dispose off his predecessor. ... The grave could be that of his predecessor, though I doubt it. Still, a possibilty. >.>