The antagonist of Cowboy Bebop: Knockin' On Heaven's Door, Vincent Volaju (Vinsento Borāju?) is the only survivor of a series of experiments conducted during the Titan War to build immunity to the lethal nanomachines that were secretly developed by the military. His plan is to release the nanomachines throughout the world, leaving only a handful of survivors. He holds the rare distinction of being one of a select few characters in Cowboy Bebop who has been able to match Spike in close combat. Watanabe said that he believes that many people would say that they empathize with Vincent and that "I even understand him." The interviewer, describing Vincent as the "most evil character in the Bebop series," asked Watanabe if Vincent was his opportunity to "show something you couldn't get away with on TV," Watanabe responded by saying that he is not saying that Vincent is "nothing more than my dark side." Watanabe added that he does not see this as a "particularly unique feature" of Cowboy Bebop: Knockin' On Heaven's Door and that all people have moments when they "lose our temper and want to destroy everything."