Aria lives an oppressed life, abused by her step-mother and step-sister, in the mansion left by her father. She is comforted only by the memories of her father, the only person who really loved her. But one day, Aria gets sick and coughs up a mysterious black liquid, which evaporates into a miasma that made everyone else in the house unconscious. Aria rushes out of the house to look for help, when she runs into a man wearing a strange mask... "I have to get out of here!!" The story of a girl suffering from a mysterious disease, and the suspicious-looking doctor who will help her search for a cure. A dark fantasy about a "strange disease" begins!!