Dr. Octo who researches octopodes decides to take over the world as he deems the eight legged creatures a more suitable master species than humans. To do this, he takes an idol singer Sumire Hoshino (aka Perman #3) hostage. Mitsuo Suwa (aka Perman #1) likes the idol dearly (as he doesn't know the real identity of his Perman partner) and becomes so angry that he transforms to go rescue her. But fighting a giant octopus is more challenging than it looks!

After bringing a fossilized egg back to life with the Time Cloth, Nobita finds himself the owner of a baby dinosaur. Everything is fine until it grows up. Nobita and friends use Doraemon's time machine to return it back to its own time.