Slaying Demons and Subduing Evil: I Have a Sacred Emperor's Decree

[749 Bureau + Demons and Ghosts + Classic of Mountains and Seas + Protagonist's Ability Is Related to Time + One Female Lead] Over the past hundred years, ancient ruins have been secretly unearthed around the world. Inside are artifacts and even "corpses" of creatures from antiquity. Within the borders of Shenzhou, they unearthed a headless corpse. Gu Yiming accidentally finds a Sacred Emperor's Token in an old house, joins the 749 Bureau, and is invited to take part in a project called "War God." (History took a sharp turn after the Ming Dynasty. This is a fictional world, so don't compare it to reality.)