At the Ryouou Academy, there is a night party called Shakoukai where "gentlemen" and "ladies" enjoy playing with each other.
In April, new student council president Mizumiya Nene and new members, Ayasaka Tabane and Mizunoha Sena, notice suspicious night parties happening on campus due to the strange behavior of the school nurse, Senzaki Kaname. They discover that the organizer is a lowly janitor named Gomi Kengo. Nene tries to appeal to the school principal, while Sena attempts to infiltrate the party, and Tabane confronts Kengo directly. The story follows whether the three can uncover the truth about Shakoukai.