Koharu Sugiura is a supporting character in White Album 2. She is a bright, energetic, and straightforward girl whose presence adds warmth and humor to the story. As a member of the school’s social circle, she often serves as a friend and observer within the central cast, helping to highlight the emotional tensions and relationship dynamics around Haruki, Setsuna, and Kazusa. Her role is mainly to provide contrast, everyday realism, and occasional comic relief.