Seikain Girl's Academy is renowned for teaching the daughters of influential families in etiquette, skills, and manners worthy of a refined lady. However, the school hides far from civilization, so many graduates receive a culture shock when they face reality outside of their homely environment.

To combat this situation, the school's administration comes up with a solution: to bring a commoner who will educate the girls about regular society. Against his wishes, the school chooses Kimito Kagurazaka to represent not only commoner life but also the male sex. He is also forced to pretend to be gay, lest a terrible consequence befalls upon him.

Adjusting to his new lifestyle, Kimito meets Aika Tenkuubashi, a reclusive girl who yearns for friends. Hoping to make herself popular, she creates the Commoner Club with Kimito to master the ways of the modern world. As time passes, they are joined by the seemingly perfect Reiko Arisugawa, the child prodigy Hakua Shiodome, and the sword-swinging Karen Jinryou. Now, as the school's "commoner sample," Kimito fulfills his duty alongside his newfound acquaintances.