Dr. Slump and Arale-chan Movie 01: Hello! Wonder Island

Professor Senbei finds a videotape of his deceased father providing instructions on how to create a love potion. The main ingredient is a tear of the evil Gyaasuka Daimao who lives at the Wonder Island. To retrieve it, Senbei takes Arale and Gatchan on a wacky adventure. (Source: ANN)