Yoshikawa Haruo is an ordinary middle school boy with few ambitions, aside from simply living a long life. As the eldest child, he resides with his three younger sisters in a home without parents. He remains entirely ignorant of his sisters' magical abilities and is said to possess some of his own, though they have yet to be discovered. One day, a mysterious yet beautiful girl appears before him. This is Mamiya Ayumi, who also wields magical powers. Her objective is to "make Haruo into a man" in order to break the curse placed upon her during childhood. To achieve this, she is compelled to work as a maid in their household. While she is adored by all the boys at school, she is despised by Kurusou Yuri, the serious, driven, and orderly class president who has harbored a crush on Haruo since they were young...