I have a theory that all the characters in MILGRAM are subversions,or at least a deeper dissection, of popular murderer tropes (not necessarily in media). They are all guilty, but there is more nuance to it than what can be initially seen.
Prisoner 01, Haruka, is the psychopath trope. It's heavily implied he's neurodivergent and has a lot of childish tendencies. His mother's abuse (which looks to be neglect) is highlighted a lot because Haruka's condition isn't the thing that pushed him to kill, it's how that condition was treated by the people around him. He wasn't given the proper care and it's that system which perpetuates the dismissal of mental health that set him off.
Prisoner 02, Yuno, tackles the abortion debate. She knows what she was going into when she entered sex work and she was willing to abort any unwanted byproducts of that work. Although she herself claims that she wasn't innocent and that she is guilty, she was taken advantage of. She was a high school student allowed to engage in compensated dating. Her reasons may have been selfish but the fact that compensated dating is a thing in the first place really detracts from her guilt.
Prisoner 03, Futa, is an online harasser and a cyberbully (for the lack of a better term). He has a strong sense of justice, but he is largely misguided. The online culture surrounding harassment rewards people for call outs and such regardless of if it's uncalled for or not. Futa was always validated by his following and never saw anything wrong with what he was doing, leading witchhunts and doxxing people. He was blinded by his own sense of justice, ego, and the approval of everyone around him.
Prisoner 04, Mu, is a victim of bullying. We are shown that she was friends with her bullies and that she may have had a crush on one of them. They didn't care about her, though, and they simply bullied her (for reasons we don't know) which led her to killing the one she was closest to. However, her behavior and attitude tells us that she herself may have also been a not-so-good person. She was simply unable to do anything because her tormentors was stronger than her. But now, with Haruka, she found someone to dominate. A person can simultaneously be unsavory and a victim of bullying, and neither of those justifies the other.
Prisoner 05, Shidou, the killer doctor. His story is still a bit unclear but it appears to have something to do with him using the lives of his other patients in order to help one person recover. A futile attempt as the person seems to have still died in the end. Rather than tackling any contemporary social issues I think his case, instead, asks us a philosophical question opposite of the organ transplant ethical dilemma. Instead of arguing for utilitarian ethics, his character argues for egoism. The question is, "Are you willing to sacrifice other people to save one life which you cherish?" and if you are then, "Will it all truly be worth it?"
Prisoner 06, Mahiru, is a selfish lover who thinks she's selfless. She views herself to be the only one giving in her relationship, wanting more from it, ignorant to the fact that her partner is unable to keep up with her and is already suffering. She keeps bombarding her partner with her everything and this, most likely, made said partner feel extremely suffocated. There was no malicious intent on her part but she unknowingly brought her relationship to a halt when her partner committed suicide. Her idea of love was severely misguided. It may have been more akin to obsession, but she genuinely believed that it was love and that it was healthy.
Prisoner 07, Kazui, is someone who we admittedly don't know anything concrete about. It seems clear, however, that he feels guilty for the death he caused because he let himself tell a destructive truth, at least to their relationship. He may have fallen out of love or not have been in love with his wife in the first place. He kept imagining and dreaming for her to break-up but she never did. In the end, he acted according to his emotions which somehow led to her death. I personally think he's gay as it would then become a case of someone so deep in the closet they try to deny who they really are which led to grave consequences.
Prisoner 08, Amane, a child brainwashed by a cult. It wasn't through any fault of her own that she committed what she had done. She was raised by, and possibly was even the poster child for, a cult and it completely warped her sense of morality and self. Her cult's beliefs are so ingrained into her that she embodies it wholeheartedly and without any doubt. Her character is a look into cult members and the cult mentality, how it permeates and warps your entire perception of the world, made more poignant by the fact that she's a child. "Does she truly deserve any blame?"
Prisoner 09, Mikoto, subverts the evil alter trope. DID has been a largely misrepresented mental disorder in media and, while Mikoto's character seems like it's following the trope, I get a feeling that there is more to it. The alter is not necessary evil nor does it kill for no reason. They're a protector who only resorted to murder to help Mikoto out of the bad situations he might have found himself in. Alternatively, it may be Mikoto himself who have committed the murders, the alter only being there to clean up the aftermath. Either way, it's all a trauma response and proper care and therapy would have helped the system better.
Prisoner 10, Kotoko, is an extremely violent vigilante. She, much like Futa, has a strong sense of righteousness and a black and white view of justice. She thinks that she's doing the right thing and that she has authority to fight for what she thinks is right. Beating up the other prisoners and sucking up to Es, however, tells us that she might be doing it more as a way to satisfy herself. Her self-worth is tied to a moral obligation to punish the people she sees as wrong. From what we saw in her music video, this may be rooted in a past trauma and overall dissatisfaction with how justice is legally served.
I may have missed some crucial details regarding their characters and I do still have a lot more to say about them but this post is so long already. But, yeah, these are my thoughts on their characters and what they represent, either as commentary or as an exploration of a popular media trope. I hope I worded it properly.
Anyway keep Yuno, Futa, and Kazui innocent please. My girlboss, babygirl, and DILF trinity amen.