Katan is one of the Cherubim. He was originally a Grigori, but was given a body by Rosiel before he expired. He worked to achieve the rank of Cherubim solely so that he could see Rosiel again. In a sense he is Rosiel's son, and he loves Rosiel deeply. He resurrected Rosiel in the hopes that he would take control of Heaven again and end the corrupt dictatorship. Unfortunately for Katan, this plan backfires, as Rosiel only cares about having Alexiel love him and tell him that he is beautiful. Unlike Kirie, Katan disapproves of many of Rosiel's actions, but he cannot bring himself to leave Rosiel's side. He considers himself already "damned" for sacrificing innocent human lives in the effort to resurrect Rosiel, so he continues his chosen path regardless of the consequences. At the Awakening of Setsuna, Katan was badly injured. Dying, Rosiel forces Katan to eat his wing, cursing Katan to one day lose his free will and become a mindless puppet of Rosiel's. Despite various cruelties and deliberate attempts by Rosiel to make him leave for his own protection, Katan stays out of love for Rosiel, and in the height of his insanity, Rosiel kills him. Right up to his death Katan continued to try and reach the remaining sanity in Rosiel and even as he died, he thought of Rosiel's suffering ahead of his own. However, their spirits are reunited after Rosiel's death.