Sosuke is the protagonist of Ponyo. He lives on a cliff by the sea. His mother is a carer in a retirement home, and his father is a captain of a ship. He was the one to discover Ponyo. When he broke the glass in which Ponyo was stuck in, his finger was cut in the process. Ponyo licked his cut, and it immediately healed, due to her having magical powers. After taking a great liking to Ponyo, he decides to keep her and give her her name, and then he promises her to protect her forever.
Sosuke is a 5-year-old boy who wears a yellow T-shirt and brown shorts. His hair is mostly black, but it is grey at the roots.
Sosuke is smart, loyal, cute and heroic.