The game takes place inside a book. The book’s story tells of the land of Muu, where the quality of dreams determined the quality of the weather the next day. Because of this, the Muu citizens invented a dream machine so they could always have good dreams. One day, an evil toad named Mamu (whose name was changed to Wart for Super Mario Bros. 2) invaded the land and twisted the dream machine into a nightmare machine. However, the Muu people learned of his weakness to vegetables and used them to defeat him.