I'm baffled that this drama isnt getting much attention because it would totally that. What can I say? I LOVED it.

---STORY---
The strongest value of this show. The storytelling is on point, tho i subtracted some points because, i'll keep it as spoiler free as possible, some of the event aftermaths didnt really make sense. Yeah, what can i expect from a j-drama but lets just say... there will be deaths in school and... the situation just immediately turns back to normal? Realistically, the school wouldve closed down. Also episode 7 felt rushed as everything puzzled itself together a little bit to quick.
Also the romance between the two characters game to short. (couuuuld be something for a possible season 2 tho? ;) )
Other than that, theres absolutely nothing to be criticized. A nearly flawless plot.

---ACTING/CAST---
Once again, ON POINT. The acting was perfect for jdrama standards and portrayed each characters emotions perfectly. Each character was designed to be compelling and interesting, no flat character design here. I even really liked the many side characters as they felt natural.
One thing to criticize is the lack of character development outside of that school. This is going to be a very subjective argument, but I wouldve loooooved to see each character outside of school as this wouldve revealed even more about their unique personalities.

---MUSIC---
The soundtrack was atmospherical and fit right into each scene, tho it was nothing too outstanding.

---REWATCH VALUE---
It is hinted that this drama is maybe getting a second season. I could be delusional here and interpret a little bit too much onto the ending but if im right here, im definetely gonna rewatch.

---OVERALL---
Good soup. Go and watch it.
No, seriously.