In the miraculous World of Demons, there lived a vampiric count. One day, standing near the statue of the Goddess of Time, the count thought with sadness of everyone's mortal fate; at this moment the God of Death appeared, telling the count he has a visitor in his castle. The visitor turns out to be a succubus named Karuru, who suggests that the count trains two young female demons, Tiris and Emalis, and sends them to the other worlds...
Angel Night has elements of adventure game (verb-based interface, menu-based navigation through the game world, usage of inventory items, etc.), visual novel (choosing answers that will influence the course of the story), as well as simulation game elements. The simulation aspect is evident in the statistics the two young girls have: depending on the count's actions, they will have better or worse training, and also might have a sexual relationship with their master.