Eiga Doraemon: Shin Nobita no daimakyô

Nobita finds a stray dog and brings him home, little does he knows that the dog is actually a prince in his homeland, a world apart deep in the African 'Smokers Forest' were the dogs evolved and have their own empire, so he and his friends take on a journey to take back the young prince to his homeland but when they get there things have changed.