One day during summer vacation, a palm-sized alien named Papi appears from a small rocket that Nobita picks up. He is the president of Pirika, a small planet in outer space, and has come to Earth to escape the rebels. Doraemon and his friends are puzzled by Papi’s small size, but as they play together using the secret tool “Small Light”, they gradually become friends. However, a whale-shaped space battleship comes to earth and attacks Doraemon, Nobita and the others in order to capture Papi. Feeling responsible for getting everyone involved, Papi tries to stand up to the rebels. Doraemon and his friends leave for the planet Pirika to protect their dear friend and his home.
The Ainsworth family's goal is to save the world from evil, but their success depends on the great sacrifice Magical Girl Miyu makes for them. Her brother Shirou, however, is not willing to let the family have his sister without a fight. That’s why he doggedly searches for a way to save not only the world but also Miyu...
