Chitose Haruna is the youngest daughter of the Haruna family and the younger sister of the protagonist, Yuu Haruna. As a second-year middle school student, she is the smallest member of the family, standing at 149 centimeters tall, with a birthday on November 29.

Chitose has a cheerful, energetic, and deeply affectionate personality. She is known for her innocent charm and a playful habit of referring to herself in the third person, which emphasizes her youthful and somewhat childlike demeanor. Despite her generally bubbly nature, she is exceptionally sensitive and prone to crying easily when things do not go her way or when she becomes emotionally overwhelmed. This combination of energy and emotional openness makes her a very transparent and endearing presence.

Her primary role within the narrative is defined by her relationships at home. She is deeply attached to her older brother, Yuu, whom she lovingly calls Yuu-nii. She looks up to him and often seeks his attention and support, acting as a source of familial warmth and comfort in contrast to the more dramatic events occurring in the wider world of the story. Her interactions are typically lighthearted and centered on home life, where she, along with her other sisters, contributes to a lively household atmosphere. While she does not possess musical abilities or play a direct role in the band that is central to the series plot, her significance comes from representing innocence and the personal, grounded side of the main character's life. Her development remains consistent with her role as the cheerful and sensitive youngest sibling, providing emotional relief and highlighting the main character's connections away from the pressures of music and romance.