When Nobita goes diving with Doraemon, a mermaid named Sophia comes close to him and they all befriend her. When they proceed towards her kingdom, they encounter a fight between two opposing tribes.

Nobita and Doraemon use time tree Mochi and catch a big bird, which has been extinct for 500 years ago. To protect the animal, Nobita and Doraemon go to Beremon Island, overseen by a golden ...