Hierarchy

Part-timer Carole meets rich girl Tuesday, and each realizes they've found the musical partner they need. Together, they just might make it.

Fuutarou Uesugi is a poor, antisocial ace student who one day meets the rich transfer student Itsuki Nakano. They argue but when Uesugi realizes he is to be her tutor, he tries to get on better terms. While trying to do so he meets four other girls.

In an alternate history where the male population is nearly decimated, eligible men serve as concubines to the woman shogun inside the walls of the Ooku.