@davefebrian:
You are almost right.
The girl is a spirit type of being who due to being treated really cruelly during life and curses gathered around her or so turned into the "evil god".
The "evil god" is a spirit type being that drew in and gathered all the negative emotions and as such negative energy in form of miasma from a large area (maybe even like from all around the world).
Due to all those negative emotions and energy that spirit transformed into a monstrous appearance in the eyes of anyone who looked at it and as such the spirit became feared as the "evil god".
This in turn strengthened the cycle of drawing in negative emotions and energy even more because everyone showed "fear" and "hatred" towards the spirit when they perceived it as the "evil god" - even moreso the heroes who intended to "slay the evil god for the good of the world".
When Kane encountered the "evil god" he was the first and only person who heard the poor spirit's cry of loneliness and sadness and its wish to be freed from that dark abyss.
That is why he tried to save it instead of slaying it.
With the help of the "goddess of kindness" Altena (who was originally his childhood friend before dying in the mountains when they were younger) Kane somehow "purified" the "evil god".
But that "purification" was only partially successful and the result is that the "evil god" was able to return to its original appearance - which is that black haired girl who Kane named "Noir".
However the spirit still has a huge amount of those negative emotions and energies gathered within it/her and also probably still has the effect of drawing in the negative emotions and energies from around the world.
So she might turn back into the "evil god" if this is not solved.
Furthermore the demon king's plans probably center around gathering negative energies even faster and hasten that process of "awakening the evil god".
And that is most likely the reason why Noir asks Kane to save her because she does not want to turn back into the "evil god".
