A stray dog turns out to be royalty from a hidden empire deep in Africa, and suddenly Doraemon's usual suburban chaos has to survive actual stakes. The first hour moves slow, but once you cross into the Smokers Forest, the movie earns every detour through hostile terrain and extinct-looking wildlife. What makes this one stick is how it finds genuine danger in a world that was supposed to be safe the moment the gadgets showed up.

Nobita finds a lost white dog and names him Peko, while his friends are hoping to spend their summer vacation adventuring somewhere nobody has explored yet. After some research, the five friends and Peko set off deep into the African jungle. There they learn that Peko has a mysterious link to their destination: he is a young prince from a remote land in the Smokers Forest, where dogs have evolved and built an empire of their own. When the group reaches his homeland, they find that things there have changed. The film first screened as a triple feature alongside Kaibutsu-kun and Ninja Hattori-kun movies.