Being a shy, timid girl, Haruka is set up with Takayuki by her friend, Mitsuki, while she is in high school. The two quickly become close, and develop an intimate relationship. 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.
Source from Wikipeida