Kirigakure Town is about to be completely flooded due to reservoir construction. After his grandmother passed away, Chen Du returned to the town where he had lived for eighteen years to keep vigil. On the night of the funeral, he received a black manual left by his grandmother.
The first page of the manual reads:
If you hear someone knocking on the coffin tonight, don't open the door.
If the knocking sound comes from inside the coffin, please find a person to keep vigil for you before dawn.
Remember, dead people don't knock four times in a row.
At twelve o'clock at midnight, there was a fourth knock on the coffin.
