During middle school, Shino was relentlessly bullied by a group of girls, including Mai Kasai. Although Mai never actively participated, she stood by as her friends emotionally and physically tormented Shino, ultimately leading to her transferring schools. Mai's family later relocated, moving her from her Tokyo high school to a rural one.
Mai initially planned to use her social skills to manipulate the class hierarchy, but her plan was thwarted when she discovered that Shino was now her classmate. Seeking revenge, Shino and Mai switch roles, with Shino becoming the new mastermind and Mai the victim of unyielding bullying.
