New Century: Have All the Knights Become Villains?

{Focusing on plot, fighting, knight version of "what if"} Traveling to a new world of knights, enjoying violent mobs and living a life of luxury, but one day a dimensional rift appeared, and what appeared one after another were... Different knight villains and a righteous knight who became a boss? What possessed me when I was dying? Is this a late system? But... Why is he a self-aware devil?