The story revolves around Aika, whose life changes after her father remarries. There she meets her stepsister, Aika, whom she initially sees as a beautiful young woman. However, she soon discovers her true personality: a foul-mouthed, spoiled, and unruly gyaru who turns her daily life into a nightmare when her parents aren’t home. Their relationship begins to change, however, when Aika starts to connect with Kta’s understanding and protective side.