Doraemon: Nobita and the Knights on Dinosaurs

The story begins with a debate between Nobita and Suneo over whether dinosaurs are completely extinct. Because Nobita's claim that dinosaurs still exist is thoroughly dismissed by Suneo using scientific reasoning, Nobita seeks help from Doraemon. However, when Nobita asks Doraemon's gadget, the "OX Divination," if there are any living dinosaurs "on Earth," he receives a negative answer. Later, to hide Nobita's test paper scored zero, Nobita and Doraemon use a gadget designed to find underground caverns and accidentally discover a vast subterranean space, which they turn into an amusement park for everyone. Meanwhile, Suneo becomes distressed after repeatedly spotting dinosaurs in the river, his backyard, and the underground space. Desperate to uncover the truth, Suneo takes a camera back into the underground but goes missing. From footage filmed by Suneo before he disappeared, Nobita and Doraemon learn that the location of the underground space is directly beneath the river in their town. They, along with Gian and Shizuka, dive underground again and witness an unexpected sight: primordial jungles from the Mesozoic era filling the vast caverns, with supposedly extinct dinosaurs roaming among them. It turns out that while the OX Divination answered correctly, it interpreted the question literally, limiting its search range to the "surface" and thus overlooking the possibility of dinosaurs existing below ground. While searching for Suneo, Doraemon and the others are captured by the Kappa tribe, a savage people living underground. Just as they face mortal danger, a knight riding a dragon appears and saves them. The knight, who calls himself Bach, claims to be a knight of the underground nation. He informs them that someone resembling Suneo has been taken into protective custody, then escorts the group to the capital of the underground nation so they can meet Suneo. During the journey, Doraemon and the others learn that the underground people evolved from dinosaurs and possess a highly advanced civilization. After reuniting with Suneo, Bach agrees to let the group return safely to the surface world, though their memories related to the underground world will be erased. However, by chance, Nobita discovers that the underground people are secretly planning an operation called the "Great Expedition," with the goal of reclaiming the surface world from humans! Unable to stand idly by, Doraemon and the others have no choice but to flee and fight back... Can Doraemon and his friends escape? Is war between humans and underground people unavoidable? And what is the true purpose of the mysterious "Great Expedition," and who are the real enemies...?