Return of the Moving Doll

847 years ago, during the First Holy War, the Hero, Anthasia Lucent used a forbidden magic spell in her final battle with the Demon King Viben. The spell sealed them in an unescapable alternate dimension, but it required the sacrifice of one of the fundamental laws of this world. The Hero chose ‘mana’, and the spell was cast, locking them with each other for an eternity.
However, living with each other made them realise that they were not so different after all. After a long time, they came to terms with each other, and devised a plan to escape. They succeeded, but the Demon King’s body was sacrificed and his soul took home in Anthasia’s body. They returned to their original world, only to find that she had turned into a vampire, and magic, in fact, had not vanished and the Holy Wars were still being fought. After finding out the truth about how magic was brought back, Anthasia understood that humanity was worthless and lost all hope in it.
Deciding that she would no longer sacrifice herself, she set out to live a calm, peaceful life, and chose to become a teacher. However, she ended up enrolling into the Hero School. But her resolve remains firm; she will live a peaceful life, not matter the cost.
But neither the World nor the Gods like it when a puppet gets too full of herself and tries to cut her strings. They want her back, right away.
In this eternal game of life and death, the Hero has yet to realise that her entire life was nothing but the prelude to her burning hell. And in this eternal game of hope and despair, the Gods have yet to realise that their actions have marked the beginning of the requiem.