Doraemon: Nobita and the Steel Troops

The film opens at the playground where Suneo proudly shows off Micross. Nobita, feeling sidelined, begs Doraemon to build him a giant robot to outshine the brag. Doraemon refuses, they argue, and he storms off through a gadget to the North Pole.

Nobita follows Doraemon to the North Pole and discovers a bowling ball sized orb that can summon parts for a giant robot. The orb hints at a shortcut to building the machine Nobita desires. He pockets the possibility as a key to victory.

Back home, Nobita and Doraemon decide to build the robot in an uninhabited mirror world accessed by Doraemon's Opposite World Entrance Oil on water. They assemble the giant automaton, but it lacks a brain. Doraemon uses a psychic controller so they can pilot it.

Nobita's mother accidentally trips on the orb and locks it away in a shed. The mishap leaves the project on hold and quietly foreshadows trouble to come.

Nobita invites Shizuka to play; Doraemon names the robot Zanda Cross after discovering its North Pole origin. When Shizuka pilots it with the psychic controller, she accidentally fires lasers at a skyscraper, destroying it. Realizing Zanda Cross is a dangerous war machine, the group abandons the robot and the mirror world, vowing never to speak of them again.

A mysterious girl tracks Zanda Cross to Japan and Nobita. She reveals her name is Lilulu and that she is the true owner of the robot, which she calls Judo. Nobita reluctantly leads her to the robot's location in the mirror world and hands her the psychic controller.

That night, Nobita investigates the mirror world, finding Lilulu leading robots building a large facility. Doraemon follows, worried by Nobita's despondence. Nobita learns the robots are preparing to invade Earth, and the two attempt to escape back to the real world. Lilulu and Zanda Cross pursue, but Zanda Cross is too large to fit through the portal and ends up destroying it, trapping the robots in the mirror world.

The next day, Doraemon discovers the orb is beeping and uses Translation Jelly to let the orb speak. The orb reveals that it is Judo, the mechanical brain meant to pilot Zanda Cross, and that it has already signaled the rest of the army to invade Earth.

Adults refuse to believe the tale, so Nobita, Shizuka, and friends recruit Suneo, Gian, and Micross to stop the invasion. They reprogram Judo with Zanda Cross so it can join them, and use Doraemon's World Entrance Oil on Shizuka's bathtub to create another mirror-world entrance. Shizuka travels to the mirror world, finds Lilulu injured and learns that Lilulu is an android; Lilulu begins to reveal Mechatopia history.

Meanwhile, Nobita and friends hatch a plan to lure the robot army into the mirror world using the mountain lake entrance. The invasion begins as the robots strike major cities around the world, but there is no one to subdue. Lilulu escapes, pleads with the army's leader to end the war, and Nobita and Doraemon free her when the leader sentences her to death.

The robots realize the entire planet is backwards and rendezvous at the lake entrance to return to the real world. Nobita and friends wait there to ambush them and end the threat. The standoff sets the stage for a final, desperate confrontation.

Shizuka, Lilulu, and Micross use Doraemon's time machine to travel back to ancient Mechatopia to plead with God and change the robots' future. They meet an elderly God, who agrees to reprogram the progenitor robots Amu and Imu so Mechatopia's history is rewritten. Lilulu volunteers to perform the rewrite, knowing it will erase her existence.

Back in the present, the robots begin to disappear as God rewrites history. Nobita and friends celebrate the apparent victory, but the absence of Lilulu weighs on Shizuka. The Earth seems saved, yet Lilulu is erased from existence.

In the wake of the rewrite, Nobita wonders about Mechatopia and looks for answers. One day he glimpses Lilulu flying outside the window, an angelic figure who seems to have survived the changes. The group barely believes what they see as she waves goodbye and vanishes into space.

During the end credits, Lilulu travels through space, giving the Earth a farewell wave as she completes her cosmic journey. Nobita races to tell his friends what he saw, hoping they will remember her sacrifice. The final image leaves Lilulu as a hopeful, benevolent presence watching over Earth.