Rudy is a kind boy with a true sense of justice. He inherited a gun from his grandfather called "ARM," which is a powerful weapon that is activated by a person's will. However, "ARM" is widely believed to be an evil power, which belongs to the demon invaders and caused the ruin of mother earth. Because of it, people are afraid of "ARM" and distrust Rudy. He has no choice but to be a wanderer because of this. As he wanders the world, he meets Jack and Cecilia, and thus begins a new chapter in his life.
