The drama's biggest problem is that it's overly ambitious with its concept. It wrote itself in a corner that was impossible to get out from. Which resulted in making the whole thing a convoluted mess. Right from the beginning within 2 episodes, you can tell this had a really poor world building, it didn't even care, shamelessly! The whole thing was unbelievable edgy especially the antagonist, he was the definition of edge lord. Let's just hope that we do NOT get a second season of this mess. Needless to say the drama isn't recommended. There are infinitely better thriller/supernatural Korean dramas out there.