Rio Mikazuki is a shinobi. That is, a shinobi living in the modern worldーa "shinewbi" of sorts. All of the ninjutsu and ninja tools of the current era are at her immediate disposal and are considerably more high-tech than before. However, it seems as though her senior partner, Igarashi, has learned how to use real ninjutsu through the long-forgotten traditional training methods of the old shinobi...