“It would be nice if this were a dream. If it’s a dream, then we can wake up… And yet, the nightmare continued.” After a life of abuse and neglect, Utsutsu Hasegawa vowed to protect his little sister, Yume. But one day after walking home from school, Yume sees red butterflies fluttering through the air. Soon after, a parasite seems to have gone into her body...then terribly transforms her into a grotesque monster that eats humans! Now the siblings’ lives have turned upside-down, where they must endure every misfortune to hold onto each other, and Yume must struggle to gain control of the monster within her...