Based on the shounen manga by Fujiko Fujio. Screened as a double feature with Doraemon: The Record of Nobita, Spaceblazer. It's spring break and everyone is going on vacation but Heroshi doesn't have any place to go but when Kaibutsu-kun receives a letter from his father saying that his father is sick he asks Heroshi to come with him to monster world, over there Heroshi turns into stone after a look on the king of that world but Heroshi and his friends do whatever they can to save him.
