Cliff, who is possessed by "Devil Power", is on a journey with Cecilia, who is also possessed by "Devil Soul". Their destination is Rouleburg, a fortress city. There is a treasure they look for in a huge basement dungeon under Rouleburg. Cliff wants it to get "Devil Power", and Cecilia needs it to remove "Devil Soul". They meet various girls along the way, at a bar or a shop, and the adventure to the basement dungeon starts now....