Heal.

In a world where an apocalypse with everything terrible and this one girl was immune, she has a group and a mythical creature stumbled upon her group while they were under attack. The mythical creature is one in a million chance of finding, and it chose the girl who was immune, leading her to the cause of this whole mess of how the apocalypse first started. The creatures are more feared than any of the known species in the apocalypse so the girl is labeled as insane. She is faced with multiple challenges and she's the answer to it all.