Famicom Mukashibanashi: Yuuyuuki - Zenpen

Once upon a time, a little girl named Chao lived in a small village in China. One night, a meteor fell near Chao's home, which burst open to reveal a monkey inside. Chao named the monkey "Goku," and took care of him for a while. However, Goku is led away and imprisoned by Oshakasama for the various crimes he has committed, and Chao sets off to find the "Gavel of Light" in order to save him. Several years later, the world is put under peril at the hands of the bull-monster Gyumaou, and Goku is called upon to save the world.