Like many others here, I got recommended this by the henti man, and since I wanted to practice my japanese I gave it a go.

As a summary, don't waste your time. This is a dumpster-fire, which gave me flashbacks of School Days, in the sense that you end up hating the main character from the bottom of your heart. The only things to praise here is the concept (I never heard about locking people with no food for a while and see who survives concept, but from other reviews seems is not that rare, so if you are familiar with this concept story might be predictable for you), the artwork and how explicit some scenes are (glad the mangaka didn't tone them down), and how this manga teases you with morbid curiosity to see what fucked up thing comes up next, which was the only motivation for me to keep reading till the end.
On the bad side we have stupid characters making stupid decisions, and a cast of awful people to hate (although some of them more than others). I have to say having backstories for all of them was a nice touch, and made their behavior more understandable (except for the main character, fuck that guy).

Overall it made me feel sick on some parts, which is more than you could say for many other works, that's why I gave it a 4 and not a 1 or 2, but I wouldn't read it again nor would recommend it to anyone. Some scenes are freaking depressing.