Kumiko: Look at me! My mother made me a new dress! Isn't it pretty?!
- —Kumiko to Sōsuke
Kumiko is a supporting character and friend of Sōsuke and a student at Himawari Nursery School in Ponyo on the Cliff by the Sea directed by Hayao Miyazaki of Studio Ghibli. Kumiko is voiced by Eimi Hiraoka in Japanese and Jenessa Rose in English by 2009.
A slender, small 5-year-old, Kumiko has short, brown, wavy hair with matching brown eyes and a pink bow tie on the top of her head. She wears a blue dress with a small, pink ribbon, and white capri-like pants or bloomers with a pink pair of shoes.
Kumiko is a sensitive and impulsive little girl who emphasizes her feelings for Sōsuke, showing him her new dress as well as requesting a ride on his boat. As a revenge for her insulting Ponyo, Ponyo sprays water on her dress. Generally, she is not the best role model among her classmates.
Kumiko greets Sōsuke at the nursery school where she shows him her new dress. Another classmate with her plush elephant comes up to him and asks him to play, however, he states that he is busy. Kumiko argues, stating he is too young to be busy, and walks away with the words, "You're so weird!".
Sōsuke then goes outside to check on Ponyo who he is holding in a bucket. Kumiko shows up behind him and tells him he is not allowed to bring things to school, to which he replies that he is not taking it on school grounds and tries to hide Ponyo in the bushes. She then peeks over and sees Ponyo, telling Sōsuke to let her see. He reluctantly agrees after she has promised to not tell anyone about Ponyo. Upon seeing Kumiko, Ponyo snobbishly turns from her direction. Kumiko gets annoyed at this and begins to insult on Ponyo's unusual appearance, which offends Ponyo and she spits a stream of water at her, soaking her new dress. Kumiko then bursts into tears and Sōsuke sees this as a chance to escape.
She later appears among the people in boats following the tsunami and asks Sōsuke and Ponyo if she can come with them, only for Sōsuke to say again that he is busy.