The story revolves around a high school student named Riko, who becomes involved with a succubus named AsuTouka (or Asu for short). A succubus is a female demon from mythology that feeds on the energy of men. Asu is sent to the human world to hunt for prey, but she ends up forming a bond with Riko.
A group known as Team Nyx released a full English fan translation patch. The translation is infamous for keeping the old-school "Ye Olde English" dialogue for the demon lords, combined with modern profanity for the soldiers. Shortly after, the game was re-listed on (a major Japanese digital store) as a "Revival Edition," sans the disc-drive requirement.