Liked beginning, middle not as much, end was fine though not great either, overall okay ish side novel to the main series with plenty of references to the main series' events, but it was still subpar to the manga. Though that's to be expected given the main series is so beloved and regarded very highly by its fans.
The idea of a school having seven mysteries, and them slowly coming upon them and it all tying back to the case from decades ago was a neat premise, but some things like the DnD game did not engage me as much (and I say that as a fan of Dungeons and Dragons).
But anyway, for the most part, it was still good.
This entire review has been hidden because of spoilers.