Ponyo and Sosuke, surrounded by water following a great storm, venture into the sea on a magical journey that gives them insights into themselves, their families, and the power of love.
Ponyo, half-fish and half-girl, becomes fully human when reunited with Sosuke, but her father has not given up on reclaiming her and seeks the opinion of the Goddess of Mercy who makes a shocking suggestion.
Five-year-old Sosuke discovers Ponyo, a girl-faced goldfish in a tide pool near his seaside home, but after he promises to protect her, Ponyo is taken by a mysterious red-haired man who appeared out of the ocean.
