Kizoku Gakuen no Fubunritsu

"In the Western Kingdom's aristocratic academy, there are countless unwritten rules."

During a dance party, the Marquis's daughter is told her engagement is broken off. Everyone acknowledged the closeness of the two, so there must be a reason for such a cruel rejection... However, Carol de la Cassata, the person at the center of the turmoil, has no idea why the engagement is being broken off. So, she decides to seek the wisdom of the student council secretary, who is rumored to be skilled at giving advice.

This is a buddy mystery in which a serious commoner secretary and the frivolous prince student council president unravel various incidents that occur at the aristocratic academy.