Light and Darke

In the land of Noctur the spirits of Light and Darke begin to die of a mysterious cause, the Great Spirit sends them into bodies of mortals, to keep them alive. Everything changes when centuries later, the spirits are reborn both as females for the first time, things begin to go wrong. A girl named Winter and her twin sister Kris are the new hosts. On their 17th birthdays the begin to fall sick; the same sickness that overcame the spirits. As they fall ill, it is up to them to find the cure, separate the spirits, and begin anew. What they don't know is removing the spirits will kill them.