Ponyo, a goldfish, sneaks away from her home and floats on a jellyfish's back. She gets trapped in a glass jar and drifts to the shore where Sousuke, a five-year-old boy, finds and frees her with the help of his mother Lisa. Ponyo licks a cut on Sousuke's finger, and he names her Ponyo. Ponyo has a family already, including her father Fujimoto, a former sorcerer who now lives underwater. He searches for his daughter Brunhilde. Ponyo uses Sousuke's blood to grow arms and legs to become human, causing an imbalance in the ocean. The Moon starts to move out of orbit and the tides become stronger. Sousuke and Ponyo reunite, and he must complete a test to restore balance to the world and allow Ponyo to stay human.