Nobita, overwhelmed by the mundane difficulties of
everyday life and envious of his friends' magical skills, wishes for a world ruled by magic. Using Doraemon’s "Madness-Ending" phone booth, he alters reality so that spells and enchantments are a part of everyday life. In this new universe, magic replaces science, allowing people to levitate objects and power their homes through incantations. However, Nobita soon discovers his own magical aptitude is abysmally low; his spells are weak, and he is constantly mocked by Gian and Suneo, while even Shizuka struggles with advanced sorcery.Frustrated, Nobita decides to abandon magic entirely, but Doraemon urges him to study. During their lessons, they meet a brilliant magic scholar, Professor Mangetsu, and his kindhearted granddaughter, Miyoko. Mangetsu has been secretly researching a terrifying apocalyptic threat: the dark denizens of the Underworld Kingdom are planning to invade the human realm. According to ancient prophecies, a legendary group known as the Seven Magic Users will rise to defeat the demonic forces. Shortly after this revelation, Mangetsu is captured by ferocious underworld monsters, leaving Miyoko distraught and desperate to save her grandfather.Determined to help, Doraemon, Nobita, and their friends use specialized magical tools to embark on a perilous, high-stakes journey into the heart of the Underworld. Their mission requires immense courage and tactical teamwork as they navigate treacherous landscapes filled with demonic traps and hostile beasts. During the grueling expedition, the group is ambushed, forcing them to rely not on innate magical talent, but on their unwavering friendship,
resourcefulness, and resilience.As they infiltrate the demon fortress, they uncover the true weakness of the Underworld's ruler: a mystical artifact that fuels the dark army’s power. Nobita, realizing that he cannot rely on powerful spells, uses his signature talent for string figures—alongside a clever diversion—to disable the artifact. With the demon king weakened, Doraemon and the group unleash a combined magical assault, shattering the dark forces and freeing Professor Mangetsu. Victorious, the heroes restore balance to the realms. Nobita ultimately decides to return the world to its science-based reality, having learned a profound lesson about appreciating his own world and discovering that true strength comes from perseverance and camaraderie rather than easy shortcuts.