This manga here my friends is pure SHIT! I usually have easy going mind and always try to find something enjoyable, no matter how disgusting a story might become but this here, just broke my shit scale!
1. No character development.
2. Full of plot holes.
3. The world seems so unreal that even tho there was a killing the previous day, the school started out normally like it's pretty common for this kind of things to happen on school premises. It's not like they got transfer to some other world because there was shown a police response at one crime scene.
4. No Enjoyment whatsoever.

My advice? Avoid this as much as possible.