About twenty years ago, a gruesome virus outbreak broke out in Beast country. No one knew what causes this virus, but this infection only contaminates the shapeshifter offspring that could not shapeshift.
One of them infected Tori, Kazuto's older sister.
Thanks to the channeling of energy and self-isolation that Kazuto did for his sister, Tori had maintained her sanity much longer than the others.
Victims infected with this virus will suffer from shortness of breath, and their sanity will slowly disappear. Once they lost their mind, their bodies would turn into frightening monsters called Windigo. These Windigoes would attack whatever was the target of their first sight.
Once a Windigo has set someone as its target, the monster will chase until it eats all its prey meat without caring for other prey nearby.
After consuming its first prey, this WIndigo would target other prey and kills other monsters that block its path.
