Miō Aida is a third-year student at Sakuragaoka High School and the vice president of the Art Club. She first met Haruki Serizawa during the school entrance ceremony beneath a cherry blossom tree, and from that moment onward they have been close friends who walk home together every day. Despite their obvious bond, a gap of ten centimeters—both physical and emotional—has always remained between them.

Miō is naturally shy, reserved, and soft-spoken. She is not comfortable talking with boys in general, but she feels at ease with Haruki. Her kind and gentle nature makes her well-liked among her peers, yet she struggles with self-confidence and tends to keep her deepest feelings hidden. Her primary motivation is her long-standing love for Haruki, which she finds difficult to voice directly. She also carries a heavy sense of guilt: Haruki’s older brother Chiaki died years ago while saving Miō from drowning, a fact that haunts her and complicates her relationship with Haruki.

In the story, Miō serves as one of the two central protagonists. Her arc centers on overcoming her hesitation, learning to express her feelings through both words and her art, and making peace with the past. As the series progresses, she gradually becomes more proactive, eventually finding the courage to confess her love and commit to a future as a professional illustrator.

Key relationships include her deep, unspoken bond with Haruki, whom she has liked since their first year. She is also close to her fellow Art Club members Natsuki Enomoto and Akari Hayasaka, who provide emotional support and encouragement. Her development is tied to confronting the tragedy involving Chiaki, resolving her guilt, and choosing to pursue her passion for painting after high school.

Miō’s notable ability is her talent for painting. She channels her emotions into her artwork, and this skill becomes a vital means of communication and self-expression throughout the series. Her artistic growth mirrors her personal growth, culminating in a career as an illustrator.