Much of Leon's history is unknown. He was once offered the opportunity to join the Braşov Coven with his sister, but declined. Following their defeat, he was shown living in Paris, where other vampires had called a hearing of a select few vampires from over the world. Lola Calwin was invited and was asked to help prevent him from using his ability to attack a group of Hunters. After Lola met him, he returned to Japan with her and joined the Firelock Coven Guard.