Doraemon: Nobita to Robot Oukoku

Nobita has been having a weird dream about a boy named Roppel and his strange companion Chami traveling in space. By a twist of fate, he met them in person where it turns out that they are real and that they were being pursued in space, causing their space vehicle to malfunction, connecting the space vehicle itself with Nobita's room. They journeyed to Roppel's planet and amidst their enjoyment, Nobita and Doraemon pledged to help Roppel's planet free from their oppressors.

Nobita went to a world of animals through the "Wherever Gas", the substance to let you travel anywhere, same as the "Wherever Door" Doraemon uses. They came across with Chippo, a boy who looks like a dog and very adventurous. A group called Numiges plans on taking over the animal planet. Doraemon and friends plan to stop them with the animal's help.

Jealous of Suneo's new robot toy, Nobita asks Doraemon to build him an even better one. Doraemon initially refuses, until Nobita accidentally discovers pieces of a mysterious robot that falls from the sky. After gathering all the robot parts and assembled them together, the giant robot, Zanda Claus, is soon completed. The duo soon learn that the robot is not a mere toy, but a powerful weapon in the fight against the coming Robot Army that is going to attack Earth and enslave the human inhabitants of it. An invasion is near, as a mysterious girl Riruru shows up, looking for the robot.

The movie is sort of a prequel to the entire series, it showed the life of Doraemon before traveling to the 20th century: How he was made, how he was partially broken, how he lost his ears, how he met the Nobi family and decides to return to the past to help Nobita.