Three girls—Haruka, Naomi, and Yukino—attend an elite women's university. On the surface, they appear to get along well, but in reality, a strict school caste system governs their relationships, defining the distance between each of them. Yukino soon becomes engaged to Junya, Haruka's older brother, shifting the group's balance of power and placing her at the center. Haruka, once the undisputed top of the hierarchy, feels her privileged position threatened, harboring growing resentment and discomfort inside. The unfolding complex relationships and how each character evolves become the focus.