When five-year-old Sosuke is playing down by the shore, he finds a goldfish with a girl's face. She is the daughter of a wizard who has renounced life on land for one in the ocean. Sosuke is smitten and names her Ponyo. She returns to her father to say that she would prefer to be human and, angered at the prospect of losing her, Fujimoto unleashes a catastrophe that threatens Ponyo's true love and his terrestrial community.