Nobita’s quest to find a pet dinosaur takes a magical turn when Doraemon’s Secret Gadgets accidentally open a time-space portal connecting modern-day Tokyo to Mayahana, a hidden, lush Mesoamerican-style civilization ruled by the Sun King. Upon arrival, Nobita is astounded to discover Prince Tio, a young royal who bears an uncanny, identical physical resemblance to him. Driven by a mutual desire for freedom from royal duties and academic pressures, the two boys concoct a daring scheme to temporarily swap lives.As Nobita navigates the opulent yet rigid lifestyle of the Sun King, dealing with court etiquette and imperial responsibilities, Tio immerses himself in the chaotic, fun-filled modern human world, marveling at video games, television, and the warmth of Nobita's family. However, this playful deception is abruptly shattered by the looming threat of Queen Latina, an exiled, dark sorceress consumed by vengeance. Latina plots to overthrow the monarchy, plunge Mayahana into an eternal eclipse, and sacrifice Prince Tio to consolidate her absolute power.When Latina’s malevolent forces kidnap Tio—mistaking him for Nobita due to their identical appearances—Doraemon, Shizuka, Gian, and Suneo rally together to rescue their friend. Equipped with an array of futuristic gadgets tailored for
jungle warfare and magical defense, the gang plunges deep into Latina’s treacherous, hazard-filled domain. Tio, meanwhile, displays remarkable character growth; imprisoned and facing imminent doom, he refuses to despair, instead using his quick wits to rally fellow captives and undermine Latina's cruel authority from the inside.The conflict culminates in an epic, high-stakes showdown at the sacred pyramid of the Sun King during a solar eclipse. Doraemon unleashes heavy-duty gadgetry to counter Latina’s dark magic, while Gian and Suneo fend off her monstrous stone guardians. In a thrilling climax, Nobita and Tio fight side-by-side, their synchronized movements confusing the sorceress. Nobita summons the courage to face Latina directly, utilizing a mirror-shield gadget to reflect her powerful dark spell back at her, shattering her staff and destroying her magical nexus.With Latina defeated and her dark empire crumbling, peace returns to Mayahana. Tio is rightfully restored to his throne as a wiser, more
compassionate ruler, deeply inspired by Nobita’s inner strength and selflessness. Heartfelt farewells are exchanged as the portals close, and Nobita returns to his normal life, forever changed by his grand adventure as the temporary Sun King.