Timid Yaya is the victim of every bully in school, but she has a secret kept even from herself: She has another personality named Nana, who is all too willing to kick butt. While nice-guy guitarist Moriyama begins a tentative romance with Yaya, the constant appearances of brash Nana reveal the truth about his would-be girlfriend. And soon Moriyama's charismatic professional-musician friend Shohei takes too much of an interest in Nana's killer singing voice . . . and body! Can Nana resist the very man Yaya has idealized all her life?!