let me start off by saying i enjoyed this immensely. this was the one anime i had the highest expectations of this season, and it partly managed to live up to it. but it is of course far from perfect.
here come the spoilers.
the first major problem is that they make it too obvious that the murderer is the teacher, by episode 3-4 it is painfully in your face obvious, stripping away the sort of "thriller" factor. the teachers motivations for killing people in the first place feel a bit vague and are presented to the viewer in a pretty clumsy manner. this all may make it difficult to take the teacher seriously. the show also tries to be quite a lot of things at the same time, i personally like this sort of thing but can see why some would just find it clusterfucky.
the storyline overall is a bit cheesy too, the whole "going back in time to make everything right" concept is pretty overused.
aside from nitpicking details whoever wrote this has a VERY good sense for tearjerkers, almost on par with jun maeda.
for something to make you cry in a show you have to catch the viewer off guard. not throw it all in your face at once and make you go "oh boy here we go, this is where i'm supposed to cry buckets". slowly build up anticipation, make you guess wrong, tears running before you know it.
i don't know how this is done specifically but all i can say is that i cried, not many shows are able to make me cry, so it did a good job on me in this aspect.
i love good tearjerkers, the original author should instead focus on his/her strength and go full tearjerker. not sure who or what company but i will research later, bookmark and hope for a good future.
