Mio Naganohara is a high school student with azure-blue hair styled in pigtails secured by distinctive wooden cube hair clips. These cubes originated from her sister Yoshino following a childhood incident where bubblegum entanglement necessitated a haircut after Mio's attempt to grow her hair longer failed. She possesses round sapphire-blue eyes and a rounded face, standing slightly shorter than her friend Yuuko Aioi. Academically capable, Mio frequently assists Yuuko with homework. She exhibits exceptional artistic talent, particularly in manga creation, often filling her notebooks with ecchi yaoi artwork. These drawings sometimes depict her crush, Koujirou Sasahara, causing her extreme anxiety about their discovery. Though fearful, her friends eventually learn about and accept her artwork. She uses the pen name "Daisuke Naganohara" for manga submissions and later achieves professional success under this alias in the CITY sequel, becoming an award-winning artist. Mio displays a complex personality. Generally cheerful and functioning as the "normal" counterpart to her friends' eccentricities, she possesses a volatile temper. This manifests in intense outbursts when provoked, particularly by Yuuko's antics or Yoshino's pranks. Her relationship with Yoshino is strained due to persistent teasing, though a childhood flashback reveals they were once close through shared kendo dojo activities where Mio first met Sasahara. She demonstrates surprising physical abilities, often triggered by efforts to conceal her drawings. These include superhuman strength enabling her to overpower grown men and remarkable leg power accidentally displayed during sports like high jump. In one incident, she exhibits extraordinary speed, coordination, and endurance: fleeing through a window, dodging trains on railroad tracks, and swimming across a river to rescue a drowning child. Her boxing skills, including a corkscrew punch, attract scouting attention from a former boxer. Mio's relationships are central. Yuuko Aioi is her closest friend, though their interactions frequently incite Mio's anger due to Yuuko's forgetfulness and eccentric behavior. Mai Minakami is another friend, though their exchanges are less frequent and often involve Mio reacting to Mai's pranks. Her longstanding, mostly unexpressed crush on Koujirou Sasahara fuels her artwork but rarely involves direct interaction. Background details confirm her birthday as March 10 in later manga chapters, resolving earlier inconsistencies in stated age potentially linked to manga contest entries. Her future as a professional manga artist is established, showing her with an assistant in later life. Habitual behaviors include reading newspapers and struggling with sports involving rules despite general athleticism.