Shin-chan's family, along with Kazama, Nini, Masao, and A-Dai, signed up for the Ultraman Anniversary Trip to the South China Sea. During the premiere of the Ultraman movie on the ship, a group of violent monkeys suddenly appeared and kidnapped the adults. The Kasukabe Defense Force was dispatched to rescue the adults. Shin-chan and his group ventured across the sea to a deserted island in the South China Sea in the hope of finding out what happened, but Aoi and Haku, who were supposed to be on the ship, suddenly appeared, and Shin-chan also discovered another strange ship...