Miharu Mikuni is a teenage girl who first appears as a third-year middle school student and later becomes a classmate of Keita Suminoe at Gakushu Senior High. She has short black hair, blue eyes, and wears glasses because she is short-sighted. Her introduction occurs when her dog, Kenta, takes Keita’s high school acceptance letter and she returns it; in that moment, Keita impulsively hugs her out of relief and stress. That hug triggers her attraction toward him, though she is inexperienced with boys and tries to keep her distance due to his aggressive twin sisters, Ako and Riko, and her own shy nature. Miharu is quiet, reserved, and prone to anxiety, often blushing around Keita and finding herself fantasizing about him in increasingly intimate scenarios despite her attempts to remain aloof. She is one of the few relatively level-headed characters in the series, frequently getting caught in the chaotic entanglements between Keita and his sisters. Her feelings for Keita grow over the course of the story, and she becomes a point of concern for Ako and Riko, who view her as a romantic rival. Keita himself becomes noticeably nervous around her, hinting at mutual interest. Miharu has a weak bladder, which leads to occasional embarrassing incidents, and she is also noted for having the largest bust among the female cast, though she remains largely unaware of her physical appeal. She is a diligent student who serves on the library committee, and her quiet, earnest personality stands in contrast to the energetic twins. Over time, she becomes more comfortable with Keita, though her inherent timidity and the external pressures from the sisters keep her from actively pursuing a relationship.