He was Prince Rei's bodyguard but betrayed him to take over the kingdom Paradiso. By brainwashing the inhabitants and destroying the kingdom's glory, he had it all in his grasp. Though Rei lost his memory, they set on a journey to find the savior - the princess who is meant to salvage the kingdom with the Magic Tiara. Valdou, however, plans on using the opportunity to find and kill the princess to keep the kingdom the way it is.
Near the end, it is revealed that he is a robotic humanoid, though whether he was always one or was once a human who modified himself is unknown. The princess, Kilala Reno, frees the kingdom's inhabitants from Valdou's control and helps create a battalion against Valdou's army of humanoid robots. He is killed by Rei in the end in a fit of rage when he (Rei) believed Valdou killed Kilala in a fire.