La Montagne mystérieuse

Goku, Bulma, and Oolong arrive at Fire Mountain, with Yamcha and Puar following closely behind. There, they meet the Ox King, who lives in the castle on Fire Mountain. The Ox King notices Goku's flying Nimbus Cloud, and realizes that he must have received it from Master Roshi. He sent his daughter Chi Chi to go to Master Roshi's island to borrow the Bansho Fan to put out the flames on Fire Mountain, but she never came back. The Ox King tells Goku that if he finds Chi Chi and returns with the Bansho Fan, he can have the Dragon Ball that's inside his castle. Goku takes off and finds Chi Chi right away. But after Chi Chi accidentally grabs Goku's tail to help herself climbed onto the Nimbus Cloud which causes him to get dizzy, Yamcha and Puar discovered Goku's tail is his only weak point. And as Goku and Chi Chi leaves for Master Roshi's island, in order to steal the Dragon Balls, they planned to grab Goku's tail to weaken him. After asking for directions from a dolphin, Goku and Chi Chi arrive at Master Roshi's island. (Source: Wikipedia)