Kugami Sugara just wants to lead a peaceful school life.
But being chosen by the beautiful and talented Shirasagi Yui to be her pseudo 'sister', her life is anything but peaceful.
And to make things even more interesting, Yui's cold but capable identical twin sister (and also student council president), Shirasagi Ui, also takes an interest in Sugara.

From there, things go as well as you might expect in this yuri comedy!