Prison lab is a mash of ideas, coupled into a nonsensical plot that derails from its own morals and tone to an astronomical degree.
Time was wasted into reading this one. The synopsis tries to sell a manga about revenge, gore, human depravity, all while not being about that at all. Of course, this can be amazing, a manga that changes course and comes to a diverse range of genres. No, this is not what you're looking for, not in any way that the premise sells.
The point of Prison Lab turned into something quite different for a moment. Morality started being explored in a much more mature light just for some chapters, mostly including side characters that didn't want death. Suspicions arise, members of the organization want to discover about a true leader. Interest grew until, something happened with the writing. Characters started to create twists that made no sense, every turn made no sense, characters acted like dumbasses. Fight scenes meant nothing when the winner had a terribly written reason as to why they won. The tone shifted so much between trying to make a good point about the world, to haha, we are quirky violent. It was jarring to say the least, terrible saying the most. The characters and story got terrible at some point.
The end of the story holds no meaning, no lesson learned. Characters go through the worst they could, wounds deep into their bodies and souls. Haha, school is fine, we chillin'. Nothing makes sense until the very end, even though some tweaks could've made it decent. Dialogue that destroyed motives, deaths that started to get funny, happening literally after they are like "Oh my god, I want to do something with my life", Bam, dead.
Prison lab is a terrible manga with decent art. Not recommended if you're looking for a good revenge manga, not good if you look for an interesting mystery. This isn't a good manga in any way you could look at it. As I said, a mash of ideas that were never developed to a good degree. A manga that tries to take itself seriously while betraying itself at every opportunity it can, in the end, destroying its own potential.
Overall: 2.7/10