A curious goldfish embarks on an adventure, riding atop a jellyfish until she lands in a predicament inside a glass jar. Rescued by Sousuke, a young boy living by the sea with his mother Lisa and fisherman father Koichi, the goldfish - named Ponyo by Sousuke - reveals her magical ability to heal with a lick. Unbeknownst to Sousuke, Ponyo is actually Brunhilde, the daughter of Fujimoto, a sorcerer of the sea. Yearning to become human, Ponyo uses Sousuke's blood to transform herself, triggering a disturbance in nature that puts the world at risk. To restore balance, Sousuke and Ponyo face a daunting trial that tests their bond and sets things right, allowing Ponyo to live as a human alongside her dear friend.