Kiyotaka Ayanokouji enters Class D at Koudo Ikusei Senior High School, joining the students judged its worst. Among his classmates are Suzune Horikita, an unsociable girl convinced her placement is a mistake, and Kikyou Kushida, a seemingly friendly class idol intent on making as many friends as she can. Horikita has a different priority: reaching Class A.
Despite its prestigious reputation and the exceptional freedom it grants students, the school reserves favorable treatment for its highest-ranked classes. Its four classes, A through D, are ordered by merit. Students cannot change their class membership, but they can improve their class's standing by outperforming those above them. For Ayanokouji and his classmates, that leaves a route out of the bottom rank. And in Class D, no method of getting ahead is off-limits.
