Papi, the tiny president of a faraway planet, escapes to Earth to avoid being captured by the military forces that took over.
Meanwhile, Nobita is making a space movie with Gian and Suneo. After Nobita accidentally destroys the set, both Suneo and Gian “fire” him. Nobita goes to Doraemon to help him create a space movie. Failed at asking Dekisugi for help (who has already been asked to join by Gian and Suneo), they instead rope in Shizuka for help, who prefers to make a movie about dolls, disappointing Nobita. Shizuka uses her favorite rabbit doll for the filming (turned into a robot by Doraemon’s gadget), but it disappears after she and the others are distracted. After Nobita’s mother rediscovers the doll, Doraemon, Nobita, and Shizuka find Papi inside it, who explains that he is the president of Pirika planet, which is currently being suppressed by a dictator named General Gilmore. Becoming a top target for Gilmore, Papi has been transported to Earth for safety by his security officer. He is offered shelter in Shizuka’s doll house. Later, Gilmore’s top officer, Dorakorule, lands on Earth following Papi, and leads an attack on Gian and Suneo’s set (thinking the model weapons and tanks to be real). Learning that Dorakorule is spying to find the ones who have hidden Papi, Nobita and his friends hide themselves from the spies (taking form of fireflies) and create a hideout in Shizuka’s house, which doubles as a factory for weapon-making. However, the hideout is subsequently raided, Shizuka is kidnapped, and the “Size-Changing Flashlight” (used to shrink Nobita and his friends) is taken, leaving the others stuck at their form. Papi offers himself to be taken in exchange for Shizuka’s safety, which Dorakorule accepts. Papi’s pet dog, Rokoroko arrives but is too late to save Papi. After explaining about himself, he, Nobita, and his friends go to Pirika to save Papi.
They arrive at Pirika’s ring system and find the Freedom Party’s hideout, where Papi and Rokoroko originated. They receive information about Papi’s planned execution the next day and proceed to stage his rescue; Doraemon, Nobita, Gian, and Rokoroko travel to Pirika using a spaceship, while Shizuka and Suneo guard the ring system. Shizuka and Suneo manage to fend off the military army and proceed to help the others. They arrive at the planet, but are raided and are almost drowned in the sea until they mysteriously return to their normal size. Meanwhile, Doraemon, Nobita, Gian, and Rokoroko arrive with the secret Freedom Party’s hideout in the planet, but are captured by General Gilmore’s soldiers. They are sentenced to execution, but moments before being killed, they miraculously grow back to their normal size and meet up with Shizuka and Suneo, realizing that they had passed the flashlight’s power limit. They proceed to battle the military army (which is no match for them due to their sheer size), and when Gilmore tries to escape, he is captured by Pirika’s citizens. Saying goodbye to Papi, Nobita and his friends go back to Earth.