The art and overall character designs in this manga are pretty nice, but since story is, of course, a major part of storytelling, I have to rate the manga pretty low because of it.

The concept in and of itself is interesting and creepy, but the actual plot gets kind of boring. It's a typical survival story of characters think they're at least somewhat in the clear and then something terrible happens again. Every chapter begins with the characters thinking they're finally ahead SOMEHOW, even if just by a single step, or they come across some kind of resource or help and it's always inevitably ruined by the end of the chapter. It's repetitive and monotonous and it seems like each chapter is more of a showcase of how the characters get screwed over somehow and have to return to point one than a journey with two steps forward and one step back.

Any survival story is going to have low points but if the characters always end up coming back to where they started, what's the point? It's like watching someone be really bad at a game and having to start at the tutorial stage again.

It's easy to argue that maybe that despair or whatever is the point of manga like this, but I'd personally say a good horror manga as at least some highs amongst the lows, and said highs last more than a single chapter.

That is to say, though, I don't necessarily not recommend it. It's still fun to look at and ultimately I do want to know how the characters get out of the situation they're in, just some of the chapters on the way can get kind of grueling to read through.