Abandoned by their abusive parents and with only each other to depend on, siblings Utsutsu and Yume Hasegawa find themselves led astray by beautiful red butterflies that have appeared in their world. Unbeknownst to them, these crimson winged heralds trumpet the beginning of a cannibalistic nightmare—a mysterious virus known as Pupa is about to hatch. After succumbing to the full effects of Pupa, Yume undergoes a grot...