Doraemon: Nobita and the Platoon of Iron Men (movie)

After finding a strange metal block in the North Pole, Nobita takes the enormous object to his house together with a strange sphere. To his surprise, metal blocks start falling from the sky and keep landing on his backyard. They are components of a giant robot that Doraemon and Nobita secretly assemble at a mirror world created by one of Doraemon's gadgets. The huge automaton belongs to a mysterious girl named Riruru. She has come here because a platoon of iron men is heading towards Earth to enslave the entire human population. Doraemon and his friends must then defeat the mechanized menace to save mankind.

Giant robot parts fell from the sky, so Nobita and Doraemon took it into the mirror world to build it and called it the Zandacross. It seems that Zandacross is a dangerous weapon so they kept it a secret. A mysterious girl named Lilulu appeared and asked for Zandacross for the invasion but she doesn't agree to invade the Earth. Doraemon and the others join forces to stop the invasion of the robot army but it seems that Lilulu is the only one that can stop it.