"Sleeping Beauty" is an American animated feature film by Disney, released in 1959, and tells the story of Princess Aurora, one of the Disney Princesses.

"Once Upon a Dream" is the opening theme of "Sleeping Beauty" and is the most famous song in the film. It plays during the scene where Prince Phillip falls in love with Princess Aurora at first sight, and its elegant and beautiful melody is successively taken over by singers – Princess Aurora, then Prince Phillip, then the chorus – building up the excitement.

This piano arrangement includes lyrics, so it is recommended to play while imagining Princess Aurora singing with hope in her heart, dreaming, and singing along with the melody (there are new and old versions of the Japanese lyrics, but this sheet music features yet another version). Embrace the waltz rhythm, play without rushing (the original tempo is approximately quarter note = 170), and feel the strong three-beat measure. For subtle tempo fluctuations, listen carefully to (and sing along with) the original song to grasp the atmosphere.