The Blockbuster Special Effects Movie: The Space Great Demon God

At home, Doraemon is doing a close-up of a dorayaki using a camera gadget, and then gets Nobita's assistance to film himself jumping for joy. Doraemon explains that with this Easy Special Effects Video Camera, anyone can combine separate images so it can project a special effects video, in this instance, of Doraemon jumping for joy on top of a huge dorayaki. Nobita decides to use this to make a film, but require manpower, so Nobita goes to Shizuka's house and ask her to star in his film. While there, he also meets Dekisugi, who also joins in as a director and scriptwriter of the film using a script he had previously written, The Space Demon King. In the story, the hero Ultra Dora-Man joins the Junior Warriors in defeating the Space Demon after the Demon destroys the Warriors' city.

Doraemon takes out the Instant Miniature-Making Camera to make miniature models of buildings, the Remote Controlled Clay and Remote to make models of the spaceship and monster, the Dress-Up Camera for the costumes and the Popping Basement to create a huge set underground. After making the set, Dekisugi stays to make the spaceship model, Shizuka goes to make miniature models of buildings, while Nobita proceeds to invite Suneo and two others onboard the production of the film. However, Nobita and the others have to avoid Gian whom they fear will try to make himself the main star of the film.

The team begin production of the film with everything ready. Following completion of the first scene in which the Demon destroys the Warriors' city, they head to the mountain to film the second scene where Ultra Dora-Man makes an appearance. Doraemon insists on playing the superhero, so the team lets him play the role. Following which, the others proceed to dress up in Warrior suits that were designed by Suneo. However, Shizuka finds that her costume is too revealing and forces him to change it.

Gian suddenly appears wondering what happened to the Demon, shocking everyone on the set. They have no choice but to invite Gian to star in the film, but have to work their way around to prevent him from learning that he had been cast in the last character remaining - the Demon. The team proceeds to film the scenes that follow, but Gian is too eager to film his scenes that he causes the team to re-film a scene where Shizuka is taken away by the monster.

With Gian needing to look after the family store, he grows impatient and pressures Doraemon to quickly film his scenes. Dekisugi accommodates Gian and reschedules the production to film his scenes first, and to convince him that a hero has to face a climax as well so he can agree in getting beaten. With Gian's scenes finished, he leaves the set while thinking that he was playing the hero in the film.

The team decides to hold the test screening of the film without inviting Gian along. But on the day of the test screening, they get a rude shock when Gian barges in and they all have no choice but to let him watch the film. Learning that he had been cast as the villain, Gian becomes infuriated and proceeds to teach the team a lesson, but they have all escaped.