I'd actually argue the opposite. I think the story is very tight and doesn't have very many plot holes and clearly explains character motivations, all of which contribute to the great themes of the work, such how peer pressure and a lack of empathy can destroy people's lives and how no one is ever completely justified as clearly right or wrong, as each of the characters commits atrocities from that they proceed to try and justify to themselves or regret having.
@MajorAlexJackson
I'd actually argue that the Main Character is Hiroshi and that Kanae is just the focal point more or less, but I think the author definitely pictures that as a moral event horizon of sorts. Her worldview is twisted because of her mental health issues clouding her judgment mixed with her limited exposure to people with strong moral foundations like Hiroshi, and so her perceptions of what justice is and what is right and wrong are based on those around her, which are primarily pedophiles, rapists, abusers, and people in prostitution. She's a complex character and I think that scene is one of the most pivotal for the entire work as it kind of inverts the perspective.
Up until that point, we all condemned Ichika for bullying Kanae and hoped she faced some kind of justice or penance for her actions. No one could sympathize with her and we all wanted Kanae to overcome her bullying, but just because you're a victim doesn't mean you're in the right necessarily, and so what she does in response flips the way the audience views the two of them, as suddenly we're sympathetic to Ichika, a character we detested, and are detesting Kanae, a character we sympathized with.
This doesn't even begin to talk about how Narumi's arc fits into this, as the woman he loves was pressuring him to participate in a gang rape he's clearly uncomfortable with and doesn't want to do, but undergoes because of the people around him and the fact he wants her to get out of that mindset. And so when she tells him that she loves Hiroshi, it destroys him and he has to live with all the guilt of the horrible things he's done for her and all the terrible experiences he's put himself through.
It's actual such a foundational moment for the story that I don't think there was a better way to do it, as fucked up as that may sound.
@Cloverfr
I think that's a very surface-level reading of what's going on here, as there's a lot of moving parts to this story based on how each person is characterized and how they justify their actions both to themselves and their rationale for them. If it was just meant to be shock-tragedy with ever-increasing odds, I don't think the author would be as detailed as she is in her characterization of everyone and exploration of things like mental health and what it takes to make good people to do bad things.
@Orange_Orange
I think that's quite similar to what the general reaction is. It's kind of like a lot of tragedies in the fact it's more about the characters and how they develop than the story itself, as we know how its going to end due to the beginning of the manga literally opening with it. I actually think that's good story-telling as other works like Oedipus Rex and most of Shakespeare's plays work off the fact the audience knows what's going to happen and how this will end to build suspense within the audience and have us focus primarily on characters and themes.
@Yeh