I don't know whether I should be glad that the solution and narrative trick at the end were actually better than I expected. Because otherwise, I could have thrown this novel at a wall and never look at it again. Good gracious!! What a dragging plot! And I don't even mean the story and setting as such. It's really entirely the plotting that made me take at least a month for this to finish. I can't even count the instances where characters were saying phrases like "Now is not the time..." or "I'm so sorry... I will tell you later"!
This was annoying the hell out of me and I took so many breaks during my reading like I never did with any other book (at least by choice). I know it's hard to build up tension over a course of 4 months and at the end it made sense the story had to take place in this time frame, but still you could write this novel in pretty much half as long or at least two-thirds. While at the end you do somewhat in a totally empathic way understand why Mei and the other classmates couldn't tell you everything from the start, the reason for Kouichi, the freaking narrator, is simply "I wanted to ask her... but somehow I felt this was not the time to do so". Like I said, simply annoying.
I could complain about the (in my opinion and compared to e.g. this) mostly missing atmosphere, but then again this was unexpectedly more mystery than horror. Even knowing there is a narrative trick in this novel I only figured out about half of it and have to admit that the old man is still pretty good at this. If only the solution wasn't the only good thing about a 675 pages hardcover novel... Well, I admit the two main characters were alright even though Ayatsuji tried way too hard to appeal to new younger readers, but then again he could have given the other characters more depth as well if he was writing such a rather long book instead of wasting the pages on barely anything in some places. There are some additions in the manga, which fits the source material perfectly compared to the anime btw, but I don't know whether those were Ayatsuji's idea or the mangaka's. Maybe I don't even want to know.
Bottom line is that I still don't know whether I liked this book or not and where it ranks in the books I've read so far from this author. I'm feeling pretty indifferent about it. I guess it would be different if this wasn't such a tiresome reading experience but I can't recommend reading the manga either because only in novels those narrative tricks really work out and since this was the best aspect of the book anyway... you might give it a try in bunko format so your hands don't drop off.