Hans Christian Andersen's The Little Mermaid

Marina, a lonely mermaid, is bored of underwater life. She wants legs. She goes to the sea witch. She is given a magic whistle that when blown, can turn her into a human or mermaid. The Prince and Marina fall in love but she can't stay with him until she can get the sea witch off her case.

Hans Christian Andersen is a little boy with a talent for making up stories. With his skill, his friends of all species, and his positive attitude, he helps brighten the lives of the people around him. This movie contains elements of many of Andersen's tales, most prominently The Red Shoes and The Little Match Girl .

In a fictional place where using the imagination is banned, a boy saves a fish, which surprises everyone by turning into a mermaid. The boy is arrested for imagining this "nonsense", and is robbed of his imagination as punishment.

Nobita asks Doraemon to take him somewhere they can dive and as a result the robot-cat uses several gadgets to make it possible for both to able to swim on an imaginary ocean above sea level. Inadvertently a mermaid ends up on Nobita's backyard when they turn off the illusion. Her name is Sophia and she is a princess of an ancient underwater civilization. Doraemon, Nobita, Shizuka, Jyaian, and Suneo quickly become her friends and are invited to visit her homeland. While heading towards the underwater kingdom they find themselves amid a conflict between the mermaids and an opposing tribe that has driven them away from their home planet thousands of years ago. Doraemon, Nobita, and their friends must then aid Sophia find a legendary sword that might bring peace once again to the seas.