Five-year-old boy name Sosuke, lives on a cliff by the sea with his headstrong mother(Lisa). One day, he rescues a curious-looking fish from the sea, names her Ponyo. Sosuke vows to love and protect Ponyo forever, but little does he know, his new pet isnt an ordinary fish.

Ponyo is actually the runaway daughter of an eccentric sea wizard. She soon comes to retrieve her. Enchanted by her first taste of the world above water, Ponyo determinedly steals her father's potions to become a human girl,and happily returns to Sosuke on the tails of a terrific storm. Her escapade, however, releases a great destabilizing magical force into the world. When Sosuke and Ponyo wake up the next morning, they find their town is completely submerged underwater.

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