This is a story that takes place before the first part and is independent of the first and second parts. Same background, different people, same pursuit, different destiny.
She lived a humble life, but she also lived a strong life; she wanted to go against the will of nature with her own strength, but she didn't know that this ending was destined from birth.
He was a powerful person, but he could not control his own feelings; until he jumped into the Valley of Broken Souls, no one knew whether it was the demons or love that was more important to him.
She lived her whole life for others, for her parents, her siblings, and her master. When she finally decided to live for herself, she paid the price of her life.
If he wanted, he could defeat anyone and claim the position of Demon Lord, but he didn't. No one is his opponent except himself.
Lifetime, eternity, perhaps, the older this story is, the more confusing the ending will be.