Takanashi Nao, a High School junior, finds herself in a quandary when she develops feelings for her handsome older brother, Shuusuke. However, her world turns upside down as she discovers that she is not related to him by blood - she was adopted as a child. Unfortunately, her brother does not reciprocate her emotions.
To her dismay, Nao has to compete with Shuusuke's childhood friend, Iroha, and the class president, Mayuka, for his heart. As she battles for love, Nao realizes that there are no rules to follow when it comes to matters of the heart.
