Siblings Utsutsu and Yume are left alone when Yume transforms into a human-eating creature. Utsutsu tries to find a way to restore her.

A boy, Utsutsu, and his little sister, Yume, are siblings who find themselves all alone. After Yume's body undergoes a strange metamorphosis-into a creature that eats humans, Utsutsu struggles to find a way to restore her.—Anonymous