Through a strange turn of fate, the exorcist, Xiao Yu, is forced to live together with Obsidian, the succubus that murdered her adoptive father. However, she's shocked to find that this succubus has lost all of her memories?! Unable to accept this, Xiao Yu decides to keep close surveillance on Obsidian, yet Obsidian doesn't seem to mind. Instead, she boldly lusts after Xiao Yu at every opportunity, even teasing her body at great personal risk to satisfy her hunger... Their lives are entangled between love and hate, yet both understand that there are greater threats making moves behind the scenes. Does it relate to the death of her adoptive father? Obsidian's sealed memories? Or is it....