Zengouku, a dark demon who always lust for destroying the human world, had murdered Natsuki's parents to usurp "The Four Gods Treasure", as known as the most powerful and dangerous weapon. However, many things had happened that made the power inside the treasure exhausted and dispersed. To kill the immortal demon, Natsuki and her comrades have to start a journey, looking for the four gods in order to recover the lost power of treasure.