Eerie National Destiny: I Studied in the Underworld

The supernatural returns, history is erased, and a global survival game based on national destiny descends upon Blue Star! Every country must send challengers into supernatural instances to survive. The higher the score, the stronger the country's destiny. The lowest score means supernatural forces invade reality. The Papal States have holy swords and crosses, Sakura has shrine-based onmyoji, and every other country has its own supernatural traditions! Only Great Xia has had its five-thousand-year legacy severed in half, leaving behind nothing but tattered talismans and City God statues. The country is on the brink of ruin. After scoring last place nine times in a row, Great Xia has seen nine supernatural domains descend upon its territory. The nation is at the brink of life and death. In the next round of the survival challenge, Great Xia has nowhere left to retreat and teeters on the verge of destruction. At this critical moment, a turning point appears! I'm Lin Jiu, a man of virtue for nine lifetimes. I planned to assist the underworld officials and ghosts with their duties in the netherworld, earning merit along the way. But an upheaval between the realms of yin and yang cut off the passage between them. The dead in the human world can no longer enter the cycle of reincarnation, and I have no way to earn merit. To change this, the Ten Yama Kings convene and use their great powers to open a passage, sending Lin Jiu back to the human world to investigate why the realms of yin and yang have been cut off. While he is at it, he is also to guide the dead to the afterlife and earn merit. But as soon as he arrives in the human world, the national-destiny instance selects him as a challenger, and he begins a supernatural survival game. Only... why does this survival game seem a little strange? Ordinary supernatural creatures see him and immediately prostrate themselves! As for the powerful ones... Heh. I'm Lin Jiu. I'm good with words, and I've got a little muscle, too. If they still refuse to listen, I'll have to call in some backup! "Ten Marshals of the Underworld! Six Offices of Merit! Lords of the Underworld! Please lend me your strength!"