Longevity: Laying Low in the Demon-Suppressing Tower, Invincible the Moment I Emerge

He transmigrates to another world in the twilight of humanity and becomes a corpse-handling coroner at the prestigious Demon Suppression Tower. No System, no hope, just an endless lifespan. Tang Xuan has only one thought: survive. Playing it safe is always the priority. You don't know if you'll die. I know I won't. A ninety percent chance is still too risky! Only one hundred percent is safe!