The title character, Nobita, is upset because he cannot get a large RC toy to show off to a rich boy, Suneo. His attitude makes Doraemon angry and, in the hot Japanese summer, Doraemon decides to "cool off" at the North Pole with the Anywhere Door, a mysterious portal.

After Doraemon has been gone for a long time, Nobita follows him, and discovers a strange bowling ball-like orb which starts blinking with a pulsating light, and summons what looks like a giant robot's foot. Nobita sleds down the hill on it and crashes into his room through the Anywhere Door. The bowling ball follows him through the door and another robot piece falls into his backyard.

Doraemon, returns covered in ice, thaws out and wakes up with a cold. When Nobita thanks him for summoning the parts for a giant robot for him, Doraemon is astonished and admits that he knows nothing about them. Using a combination of the Opposite World Entrance Oil and the Roll-Up Fishing Hole, they transfer to the World Inside the Mirror, an alternate mirror world without people, and build the robot. Nobita dubs the robot "Zanda Claus" because he feels that the bowling ball that summoned the robot parts was a gift from Santa Claus at the North Pole.

Using a brain wave controller that Doraemon pulls out of his pocket, he and Nobita play with the robot and make it to do gymnastic maneuvers. Nobita returns home and brings Shizuka back with him to play with the robot. However, Shizuka presses a button on the control panel that makes the robot fire a huge laser beam, resulting in the destruction of half of the city. The group realizes just how dangerous Zanda Claus really is, and they decide to return to the real world and forget about ever finding the robot.

However, Nobita has forgotten about the bowling ball-like orb that he brought back with him, which has been sending telepathic messages to a mysterious girl named Lilulu. She is the owner of Zanda Claus, and is looking to reclaim the robot. Following the orb's messages, she seeks out Nobita, who accidentally reveals that he knows about the robot.

When Lilulu forces him to show her where it is, Nobita borrows the Roll-Up Fishing Hole from the spare pocket that Doraemon keeps in the closet and takes her to the World Inside the Mirror. She reclaims Zanda Claus, and asks Nobita if she can borrow the Roll-Up Fishing Hole for a while. Nobita agrees.

Nervous about what Lilulu is up to, and curious after seeing two shooting stars in a row, Nobita uses the Bamboo 'Copter to fly over and investigate. Flying over the forest by Mt. Ura, he discovers the Roll-Up Fishing Hole unrolled and a portal to the World Inside the Mirror open. When another shooting star falls from the sky directly into the portal, Nobita follows it into the other world and discovers that it is one of the parts for building a massive robot army and that Lilulu is at the center of it all.

Doraemon, suspicious of Nobita's peculiar behavior at home, follows him to the forest. He uses a long-range Paper Cup Phone to listen in on her, and discovers that Lilulu is actually a robot who hates all humans. Lilulu discovers that Nobita and Doraemon eavesdropped on her and chases them. After Nobita and Doraemon return to their own world, Zanda Claus tries to get through the portal as well, which results in its destruction, seemingly separating the two worlds forever.

Nobita and Doraemon have forgotten about the bowling ball orb that is still at home. It wakes up and begins bouncing around. Doraemon pulls out a special kind of incubator and puts the bowling ball and Doraemon's Translation Jelly in it, causing the bowling ball to hatch into a cute yellow peep the group names "Pippo" (one of the onomatopoeias to describe the sound a peep makes in Japanese). Doraemon warns Nobita about a giant robot army involved in a plot to enslave all humanity, so that robot-kind can take over the Earth.

Nobita becomes good friends with Pippo, and Shizuka takes care of fixing Lilulu when she becomes very badly damaged. Lilulu had some traumatic experiences as a child, and she holds a very deep distrust and resentment towards humans. The only individual with whom she feels connected is Pippo, whom she fixed "on a whim" after he was broken by the other robots. Despite everything Nobita and the others do for her, Lilulu still shoots Nobita with a laser beam from her finger. Pippo jumps in front of Nobita and is very badly injured, which gives Lilulu a wake-up call.

She changes her mind and decides that she is not going to tell the robot leader why there are no humans on the planet or where they are. The rest of the robot army chains her up for her heresy to people, and tortures her to get her to reveal what she knows. Nobita, Doraemon, and the others arrive with Zanda Claus and rescue her.

Back in the real world, Lilulu reveals that she is having an inner conflict with herself and doesn't know what she wants. She willingly lets Doraemon lock her up in a birdcage using the Small Light.

In the meantime, the robot army becomes suspicious because of the lack of humans in the world. They discover that they are in a fake world after analyzing the satellite image of the world, then comparing the image to another image of the current world, and seeing how they are reversed. They return to the lake where they entered the fake world, sure that it is the connection doorway. Doraemon and the group intercept the army at the lake.

Lilulu and Shizuka remain at Shizuka's house to have a talk, which gives Shizuka a brilliant idea to save the world. She re-enlarges Lilulu, using the Enlarging Torch Light, and they both use the Walk-In Mirror to return to the real world. Using the time machine, they return to 30,000 years ago on Mekatopia, attempting to talk to the professor who created the robots from which the robot army is descended. The professor plans to redo everything by removing the competition instinct from his robots, replacing those instincts with instincts of humanity and love. He collapses before he can finish his job. Lilulu, in order to complete the salvation, disregards the fact that she and Pippo will disappear after they redo history, and she continues the reprogramming with instructions from the professor.

Back on Earth in the present time, the robot army, larger in number, has taken the upper hand. Zanda Claus is heavily damaged in the process of destroying the leading ship of the robot army. Lilulu, back at Mekatopia, has nearly finished her job when the professor dies. At first, she doesn't know what to do, then she figures out that she needs only to add her feelings, her love from Nobita and his friends, including Pippo. The job is completed just in time. The robot army is reinforced and attacks en masse. The reprogramming was successfully completed, and the robot army is completely erased, as are Lilulu and Pippo. Shizuka uses the Everywhere Door to return to Earth, rejoining her friends with sorrow.

The next day, the group is back in the real world, and Nobita is back in school. This time, he chooses to stay, and Doraemon arrives to talk to him before going to the baseball field. While Nobita wonders if Lilulu and Pippo may ever be resurrected, a shadow crosses his eyes and Lilulu appears with wings on her back. The wings take the appearance of Pippo in the form of a giant Phoenix. They visit Nobita with cheers, then vanish once again into the air. Nobita believes it was Lilulu and Pippo who appeared, and he runs to the field to tell his friends.

Referensi: Wikipedia