Just don't read this. Spoiler/Trigger warning: It's about twelve and thirteen year old girls being gang raped to death. The only difference between different volumes is a slightly different backstory or hair color for the young girl and how many days before she dies of massive internal injuries and sepsis. Oh, also, the grown men who are gang raping the little girls, in every single chapter, abuse and torture them in creative ways. So that's another difference between chapters, I guess. Sometimes the girls almost escape, but they never do. In one of the first chapters, the girl gets her eye pulled out by one of the rapists. Then she's raped by fifty more men that day. Then she lingers for days more of being raped, before she dies.
So, uh: Trigger warning. Ya think?
Also, in the manga, the reason the government has these girls killed is to keep peace in the prisons. The author makes his world-view explicitly clear in the entire series. That is: All men have an instinctive need to rape women and children, and if their need to rape is not satisfied, they destroy the social order. Any men insulted by this? At all?
You would think that, even if the prisoners were all going to go full-on Attica if they didn't get laid, the government could have just hired prostitutes and given them a reasonable workload and some assurance of safety. But no, the "only possible" solution is to throw pre-teen girls into the prison yards and leave them there until - and only until - they are dead.
What is wrong with this guy? This manga is stupid and perpetuates the idea that men are hard-wired to rape.