Rei, Kazusa and Banri are close childhood friends. Rei, who's better than any guy, the cool and smart Kazusa and Banri who's mischievous and bright have the perfect balance. It's normal for the three of them to be together all the time and without thinking of themselves as men and woman they're just together. But something happens after which Rei starts to think of Banri as a "man", so the relation of the three changes...?!