Shin-chan gets kidnapped by actual criminals, and the movie treats this with the comedic seriousness of a five-year-old's fever dream. The whole thing is a kidnapping heist that collapses the moment Shin-chan realizes nobody is actually stopping him from being Shin-chan. You're watching competent adults get systematically dismantled by a kid whose superpower is having no respect for the bit, all to find treasure that probably isn't even real.

A criminal band wants the fabled treasure of Treasure Island, but the key to its vault is guarded by a small boy. The group travels to Japan and mistakenly kidnaps Shinnosuke Nohara, who is the image of that child. The villains are the secret society White Snake, and they seize both Shinnosuke and his look-alike, Prince Sunnokeshi of the Buri Buri Kingdom, to reach the riches hidden beneath the golden palace on an imaginary island in the Indian Ocean. Shinnosuke's parents, Hiroshi and Misae, team up with Lulu, a major in the palace guard, to fight White Snake and win back both boys. The film is a comedic adventure with the franchise's slice-of-life and ecchi flavor.