As a child, Sasami Aoba fantasized about becoming a defender of justice, like the magical girls and "Sentai Rangers" she admired on TV. Years have passed and now Sasami has become a police officer herself. Her first assignment is to infiltrate Hanagaki All-Girls High School and ferret out any trouble she may find. On her first day posing as a student, Sasami is shocked to discover that an apparent book thief at school is actually another undercover police officer, Sakuraba Midori. What's more, Midori insists that she herself is the officer in charge of the school, not Sasami. Will the two girls become rivals, partners...or something more?