The main character is a girl who is plunged into a nightmarish situation in a building. The 'angel of death' is a major character that she has to deal with. He is not like a typical angel but rather a figure of death and danger. There could be other characters as well, like perhaps people who are somehow related to the building or the situation she's in, but the girl and the 'angel of death' are the two most prominent characters in the story.