Keita is living any junior high school boy's dream. He has two older twin sisters, Ako and Riko, who compete for his romantic love in many ecchi ways, like good morning tongue kisses and abundant panty flashing. Their parents openly support the sisters' feelings and advances, because they are step-siblings and not related by blood. In fact they even have a bet going as to which sister Keita will choose. And since the sisters and Keita attend the same high school, there are bound to be numerous misunderstandings.