Man, what the hell, or rather, I didn't really her walking into the actual underworld coming. This series is always a treat.
Thank you for the translation.
TL;DR Mieruko-chan except she's much more jaded and everything is fucked (for now) because essentially the entire town has been marked for death.
From what I understand she was a fear junkie trying to find something that would scared her as ghosts weren't cutting it. Ended up getting marked for death (as seen by the reflection of her death in the skeleton ghost eyes). So now she's on a quest to figure out what's causing the abnormal paranormal stuff in addition to everyone killing themselves. The guy tagged along because he doesn't see the ghosts but understand the town is under threat by these paranormal forces.
Edit: Every time a character's face turns smoky / a dark mist that's the spiritual representation of their soul being corrupted / death.
Been a while since any kind of horror gave me the chills. There’s something really claustrophobic about being a ghost here. You’re just stuck in a dank purgatory and all around you is a black void.
If you walked off the edge, who knows how long you’d fall.
It really gives the vision that she is at the edge of an endless abyss, but I think she it's actually a dried riverbed of the dead river that is the source of the whole problem.