Doraemon: Nobita and the Steel Troops

Nobita travels to the North Pole using the Anywhere Door and accidentally discovers robot parts. Because the parts are too large, he and Doraemon take them to the Mirror World, an uninhabited dimension, to assemble them. Once completed, Doraemon names the robot "Christmas Samurai." While happily operating Christmas Samurai, they inadvertently discover that it is equipped with devastating missiles. In the real world, Nobita meets Riruru, who claims to be the owner of the robot, and borrows a gadget that allows access to the Mirror World. Later, Nobita and Doraemon discover that a base for attacking Earth has been established in the Mirror World! The commander turns out to be Riruru, who was actually sent by the Mechanical Utopia as a robot to guide the Steel Troops to Earth. To save Earth from this crisis, Nobita and his friends decide to fight the Steel Troops. After Riruru is injured and saved by Shizuka, she discusses with Shizuka how conquering Earth is wrong. The Steel Troops, unable to wait for Riruru's contact, have already arrived on Earth in large numbers, so Nobita and his friends begin fighting them in the Mirror World. Moved by Shizuka, Riruru seriously reflects on the wrongdoing of their actions. She then teams up with Shizuka to travel back 30,000 years to find the human scientist who created the ancestors of the Mechanical Utopia, attempting to modify these ancestors so that their descendant robots will not desire to conquer Earth.