In high school, Haruka was a reserved girl who became romantically involved with Takayuki through the help of her friend Mitsuki. They soon developed a deep connection, and Haruka discovered a passion for collecting picture books.
Very early on in the series, she is involved in a serious car accident and ends up in a coma. The main thrust of the story begins when she awakens three years later. She is afflicted with anterograde amnesia, and because of her delicate psyche, her family and Takayuki conceal the truth that three years have passed, which forms much of the tension in the series.