After reading her father's final words, a young girl named Airu begins to worry about her family name. She is worried about her brother, who is a prefect at a prestigious school, and her sister, who has fallen in love with the head prefect of the school. Airu tells her mother that she is determined to fight against her brother. He tells her that he has not been able to defeat his brother on his own, and that he is certain that she will have to beat him by force if she wants to leave the family