On the continent of Lorennia, there is such a mysterious family.
The eldest sister of the new generation in the family will be carefully trained to inherit the entire family and become the supreme saint in the future; while the rest of the family will be thrown into the dark valley where the demons live from the age of six. Only those who have successfully spent three years in the dark valley can be taken back by the family and assist the saint with powerful magic power.
In 657 AD, the only remaining saint in the family gave birth to twin sisters and became infertile. As usual, the elder sister was carefully cultivated as the heir, while the younger sister was thrown into the dark valley. In 666 AD, my sister was taken back to the family, but was expelled from the family because she possessed the power of Satan. The younger sister returned to Dark Valley and became the leader of the demon world with her own strength.
In 700 AD, Lamont received a letter asking for help, asking him to help the Saint change the ending.
The story begins from here
Intent: Redemption in darkness