At a young age, Jun was very talkative and cheerful. However, due to her believing she was the cause of her parents divorce, she believed she spoke too much. As a result, she can barely force herself to speak at all, due to fear.
She tries her best to avoid any interactions with others, due to her inability to properly communicate. However, she yearns for a way to communicate her feelings.
Her life changed when she met Takumi Sakagami. She believed that he was "peeking into her heart", and because of him, she learned she could communicate her feelings through song.
Over time, she gradually came out of her shell, and by the end of the movie, was able to communicate normally.
Jun Naruse is a short girl with short black hair and grey eyes. Most of the time, she wears a seifuku consisting of a white long-sleeved top with a collar and grey buttons, a white shirt underneath with a collar with what appears to be a light grey butterfly on it, a grey bow around the neck, a long white skirt, a pair of black tights and a pair of brown uwabaki.