Mio Kagawa is a supporting character in A Star Brighter Than the Sun. She is a first-year student at Kitano High and a classmate of the protagonist Sae Iwata. Mio is known for her calm and rational demeanor, often described as the reliable anchor of her friend group. She has a strong-willed personality and speaks her mind clearly, which helps keep those around her grounded. Her primary role within the story is to act as a supportive friend to Sae and a steadying influence on Hisui Onodera, who tends to get carried away when discussing romance. Mio’s motivations stem from a desire to maintain harmony and offer sensible advice among her friends. Her key relationships are with Sae, whom she supports through her romantic uncertainties, and Hisui, whom she gently guides. While Mio does not undergo a major personal transformation over the course of the narrative, she consistently provides emotional stability and clear-headed perspective to the group. Her notable abilities include her straightforward communication style and her capacity to remain level-headed in emotionally charged situations.