Oolong the Terrible Dragon Ball: Doragon bôru : Season 1 Episode 4

Goku and Bulma arrive at a certain village, where the fifth Dragon Ball is located. Goku is mistaken for the freely shape-shifting monster Oolong, who raids the village, and is hit by a sudden attack from one of the villagers! Bulma makes a promise with the villagers that “We’ll take care of Oolong in exchange for the Six-Star Ball that’s in this village”. Goku disguises himself as one of the village girls, and the captured monster’s true identity turns out to be a piglet, of all things!! Bulma and Goku obtain the Six-Star Ball. Taking in Oolong as their ally, they continue their adventure to find the remaining Dragon Balls!!