Growing up with an abusive father, Utsutsu is highly protective of his younger sister Yume. One day, she contracts the strange Pupa virus and begins to sprout grotesque wings and attack both animals and humans.
After school Yume tries to walk home with her brother, Utsutsu, but he tells her to wait at the park for him. On her way to the park Yume meets Maria and she tells Yume to head home before she sees 'Red Butterflies'.
