Due to family problems, Hirayama Hayaka transfers from a private high school to an industrial high school. However, upon entering the school, she finds out that there are 850 boys in the school, and that she is the only girl there. Apart from the great disparity between the number of boys and girls, she also finds out that gangsters still exist in this era. Furthermore, a conflict has erupted between her classmate Katou Yuuni and the gangsters. Thus begins Hayaka's eventful life in the industrial high school...