From Boku-Tachi:

Assobot Goku is the strongest and worst assobot there is, and he and his gang take what they want without remorse. But when he sets his sights on Miroku Village, and meets up with a mysterious young man named Sanzou playing a strange harmonica, he gets more than he bargained for. How does Sanzou know about Goku, and how are they both connected with a prophecy foretelling the destruction of the world? "Assobot Goku" first appeared in Weekly Shounen Magazine in issue 4/5 2002, and has since then been made into an animated series called "Assobot Senki Goku" (The Assobot Fighting Chronicles, Goku).