Ari is the main antagonist in the Salvation Arc. They were a soulless vessel who's only memory was being discarded. They eventually tried to interact with the light world but becuase their souless, they cannot be seen or heard almost like a ghost. After words they managed to find the Dark World where only Darkners can see and hear them.  Soon they found out about a prophecy one that mention that if Light and Dark's balanced would be shifted, it will result in the world's destruction. They eventually went under the alias "The Knight". After they heard that the  Eastern Fountain been sealed, Ari went back to the Dark World and attempts to not only kill Kris, Susie, Ralsei, Lancer and Noelle, but also overthrow the 4 kings, and destroy the lightner world by using Kris SOUL,  Seam and Jevil's magic. and Noelle's weapon.