Keyword Demon Lord

When a low-ranked fairy accidentally resurrects a powerful demon, their fates become cosmically entangled as the world is thrown into turmoil.

The age of the demons has begun. Dr Faust has foreseen this rise of evil. Unfortunately, he is near death and is unable to personally battle this upcoming threat. Faust entrusts a young boy, Shingo Yamada, to take the responsibility of ridding the Earth of this new evil presence. Faust finds a birthmark on Shingo's forehead that signifies that he is the chosen demon fighter. Faust summons from hell what may be humanity's only hope of surviving: a less than enthusiastic devil named Mephisto rises. After signing a pact in blood to save humankind, Shingo and Mephisto set out to battle the supernatural world.

It tells the magnificent Xianxia story of Wei Zhi, the female protagonist who is reincarnated as a phoenix, and Yan Yue, the male protagonist who is the Sun God. They go through hardships and finally break the destiny of how the "phoenix nirvana will shake the three worlds" and rewrite their own Xianxia story together.