When Nobita feels like diving in his hometown, Doraemon uses a Underwater Pump Simulator to pump all the water out of Tokyo, causing the entire city to go underwater. That night, Doraemon and Nobita use a Diving Mask Simulator to dive underwater. Later on, lots of fish, and a shark attack Doraemon and Nobita. So, Doraemon puts a stop on the Underwater Pump Simulator, but there is a girl named Sophia, lying down on the bushes in his neighborhood.
Doraemon the Movie: Nobita’s Great Mermaid Naval Battle (ドラえもん のび太の人魚大海戦, Doraemon Nobita no Ningyo Daikaisen?), also known as Doraemon the Legend 2010, is a 2010 Japanese film that was released on March 6, 2010. This movie is part of the celebration for the franchise’s 40th anniversary and the 20th anniversary since the first Doraemon film. The film was released theatrically in selected cinemas in Singapore on December 9, 2010 in Chinese Language.