Pupa

ピューパ

After their parents abandon them, Utsutsu Hasegawa devotes himself to protecting his younger sister Yume, the one person he has left. When the siblings glimpse a swarm of red butterflies, both are infected by a virus called Pupa that turns the body into a flesh-hungry creature. Yume mutates into a monster driven to feed, while Utsutsu gains the power to heal any wound and regrow lost limbs. He offers his own body as her food, enduring repeated dismemberment so she can survive.