Shuri Wakatsuki and her twin brother Syūsuke were close friends of Sana Hidaka before he moved away.
Shuri, along with Shuusuke, are abused by their father who is obsessed with being promoted. They live with him, along with a woman who lives with them for father's money and sex. Their real mother died prior to the beginning of the series. To hide the truth about their torn apart family, the twins act silly and light-hearted when in the presence of others.