Momoko, a female college student, is eager to begin her student teaching at her alma mater—a crucial step toward becoming the teacher she has always dreamed of being. However, the school has since transformed from a co-ed institution into an all-boys' school, and the class she is assigned to—Class Z—is a special group filled with problem students. To make matters worse, Machiko, an unmarried senior teacher, sets a condition for granting her the necessary course credits: she must improve Class Z's academic performance.