After a theme park that revives extinct dinosaurs is opened in Tokyo, Shinnosuke's pet dog, Shiro, crosses paths with a small dinosaur. The two befriend each other, but their friendship might affect the existence of the park.

Shin Chan gets his mother to finally buy him the last Ultra Hero sword, but when he opens the package there is only one rule inside. In addition to this confusion, Shin Chan meets Tostado, a dog just like Nevado but in black.