The "tomb-guarding mark" on Lin Jiuchen's chest led people to declare, from the time he was a child, that he was born to guard a tomb. He was destined to protect an ancient Black Tortoise coffin. If he ever left, the blood curse would strike him down each Yin month, and he would not live to see twenty-five.
Lin Jiuchen wants to break free of his fate, but before his death, his grandfather sealed away every clue, leaving him only these words: "If the Dark Coffin opens, disaster will befall the world. The tomb guardian must not leave..."