Don't be afraid of ghosts knocking on the door in the middle of the night (also known as The Ghost King Called Me to Patrol the Mountain, also known as the Eighteenth Floor Law Enforcer, and also known as the Yin Soldier's Business Trip Diary): In the year XXX AD, the conflict between the underworld and the human world increased sharply, and the relationship between the two parties deteriorated sharply. Some of the top scientists and secret organizations in human society used advanced high-tech technology to begin capturing ghosts in large numbers for research. The underworld is facing unprecedented challenges. The number of sinful ghosts in the eighteen levels of hell has increased dramatically, and the overload operation has brought the entire underworld system to the verge of collapse. In order to reduce the pressure on hell and prevent further interference from humans, the underworld decided to send thousands of underworld soldiers to the human world to enforce the law...
The idea is interesting