Everyone who dies for no reason carries a deep resentment at the moment of death. The resentment of these unjustly killed people gathers and coalesces, following the person who harmed them until heavenly retribution finally arrives.
You should know that cause and effect govern the world. The cycle of karma never fails. It is not that retribution will not come, only that the time has not yet arrived.
Perhaps even Heaven could no longer bear the immense resentment. After lingering for ages without ever dissipating, it was nurtured over a thousand years until it melded into one, and at last, something was born.
He is Hanchuan, an entity formed from resentment. As long as his obsession endures, he cannot die. And his obsession is the hatred and murderous intent toward the demon called Muzan Kibutsuji, shared by countless vengeful spirits united as one.
** ** **
Hanchuan discovered that humans were truly warm creatures. Their love made even him, a being made of resentment, feel immeasurably warm. For one brief moment, he thought, If only I had been born of love.
So he was willing to do everything he could for a group of people like them.
** ** ** **
He is an embodiment of resentment, immortal and able to hear the words of the wronged dead. Everything he knows about living among humans was taught to him by those spirits, whether Breathing Styles, swordsmanship, or how to guide those who came from other worlds. He owes it all to the spirits who taught him.
Theme: For the sake of all that is beautiful, even as a vengeful spirit, I will protect the beauty of this world.