Doraemon Movie 07: Nobita to Tetsujin Heidan

When Nobita discovers enormous robot parts falling from the sky, he and Doraemon secretly carry them into the Mirror World and assemble a giant machine they name Zandacross. Their exciting discovery turns frightening when a mysterious girl named Riruru arrives searching for the robot and reveals that it belongs to a mechanical civilization preparing to conquer Earth.

With the invasion approaching, Nobita, Doraemon, Shizuka, Gian, and Suneo must use the Mirror World to keep the enemy away from ordinary people while confronting an army far beyond anything they have faced before. Riruru is torn between the mission she was given and the compassion she begins to feel for humanity, making her choice crucial to the fate of both worlds.