Erika Klause was separated from her brother when she was little. Determined to meet him, she decides to enroll at Rosenstolz Academy, where she is sure that she will find him. But, on the first day of school, she accidentally meets the five Strahl candidates. Since assistants of the Strahl candidates gain access to the boys' dormitories, Erika becomes determined to become an assistant in order to find her long lost brother. What awaits Erika at Rosenstolz Academy?