This is the first manga I've read by this author, after hearing about him on youtube. I feel like the premise is really interesting, but in execution it comes off as a bit... abrupt? The MC's dreams were basically just exposition dumps, explaining exactly what the holes were and how they function. It would have, I think, been scarier if that was a mystery. Or maybe if it had been told to us through the perspective of someone who had already entered.
That's just me nitpicking, though. I'll definitely be looking at some other work by the same author!