Doraemon Movie 25: Nobita no Wan Nyan Jikuuden

Nobita rescues a drowning stray dog and names him Ichi. Soon one abandoned animal becomes many, and hiding all the cats and dogs from adults is impossible. Doraemon and the others decide on a radical solution: take the animals 300 million years into the past, give them the means to survive, and return to visit them later.

A time-space disturbance ruins that plan. When the friends travel back, they land 1,000 years earlier than intended and discover that the animals' descendants have built an advanced civilization of their own. Their time machine is damaged, Ichi is nowhere to be found, and an asteroid catastrophe threatens the new world. Nobita's promise to his first stray friend becomes the heart of a journey across hundreds of millions of years.