In Ponyo, the little boy who befriends Ponyo is named Sōsuke, often written as Sosuke in English text.
Sōsuke is five years old and lives in a seaside town with his mother, Lisa, while his father, Kōichi, works at sea. He discovers Ponyo after she becomes trapped in a glass jar near the shore. When he frees her, she licks the blood from a cut on his finger and quickly heals it. Sōsuke then names her Ponyo and promises to protect her.
His kindness becomes central to the story. Ponyo wants to become human, and her transformation releases enormous magical energy that disrupts the balance of nature and causes a tsunami. Sōsuke remains loyal to her even when she shifts between fish and human forms. Gran Mamare ultimately tests whether he can love Ponyo regardless of her form, and he says that he can.
Toki is one of the nursing-home residents, while Fujimoto is Ponyo’s wizard father and Gran Mamare is her mother. None of those names refers to Ponyo’s young human friend.