Midori is a human elementary school student in the futuristic world of Astro Boy. She is a classmate of the robot boy Astro. Her name, Midori, means green in Japanese, and she is often seen wearing green clothing. She has brown hair and brown eyes, and she always wears her hair in high-set pigtails. Midori is outgoing, well-spoken, and friendly. She is one of the first human children to befriend Astro, immediately welcoming him into her friend group and helping him feel accepted. She often takes the lead on class projects, demonstrating her social confidence and organizational skills. Her motivations are typical of a young child: she values friendship, enjoys school activities, and shows a natural openness toward others, including robots. In the story, Midori serves as a peer and friend to Astro, giving him a sense of normal childhood experience and reinforcing the series' themes of coexistence between humans and robots. She interacts with other classmates such as Kenichi, Tamao, and Shibugaki, and her key relationship is with Astro, whom she supports without prejudice. As a supporting character, Midori does not undergo significant personal development across the series, but her steady friendship illustrates the power of acceptance. She possesses no superhuman abilities; her strengths lie in her sociability, kindness, and ability to bring people together.