Miyako Yatsuhashi faces an unexpected challenge after volunteering to be her class representative. Yatsuhashi has always attempted to set a good example for her classmates and the whole school to follow. However, when she is seated next to Reika Miyakonojou for the year, Yatsuhashi finds out that her classmate is the exact opposite of her.

From being far too blunt to not wearing panties, Miyakonojou embraces being an extreme sexual deviant. Refusing to accept this way of life, Yatsuhashi takes it upon herself to turn Miyakonojou into a more dignified young woman—all while avoiding her amoral influence.