Voiced by: Katsuyuki Konishi (Japanese), Jason Liebrecht (English)
The Baron of Luxor and Ion Fortuna's foster brother, Radu is Ion's most trusted friend and is chosen by the Empress to accompany Ion on a mission to negotiate with the Vatican. The visit is ruined when a terrorist bomb causes the Vatican to believe Ion came to kill Cardinal Caterina, and Father Tres attacks him. Abel and Esther meet with Ion and realize it was Radu who set the bomb and betrayed Ion. As a member of the Orden, Radu was given the orders to kill Ion and Cardinal Caterina, to cause a war between the Empire and the Vatican. Radu appeared to be killed by Sister Paula, but he reappears a short while later injured, but alive. Note, Sister Paula's appearance in the Iblis arc is only in the anime.
With Dietrich's help, he seizes control of the Inquisitorial Department's weapons and turns them on the city of Carthage. After Radu severely injures Ion and Brother Petro, Abel activates his 80% Crusnik nanomachines, and kills him. Radu's sun-burnt dead body is retrieved and repaired by Dietrich, using artificial blood and skin, turning him into a puppet. Though Radu manages to return to his old self to stop Dietrich from using his body to kill Ion, Dietrich is able to quickly regain control and says Radu is no more. Radu's body is destroyed for good when Seth, in her Crusnik form, disintegrates him.
Radu possesses the unique ability to produce and control blue flames from which he gained the nickname Flammenschwert (flame sword). After he is turned into a puppet, Dietrich gives his blood the ability to burst into flames. Radu's fire production and manipulation abilities are due to his being a rare breed of vampires known as Efreet.
In the manga adaptation, Radu appears to be more reluctant in serving the Order, appearing horrified when he finds out about Dietrich's use of vampire corpses in the creation of the "Death Hunters".