English is not my first language, so sorry for the mistakes
They messed up a lot in the beginning, but it got more interesting and better narrated once the focus shifted to her sister. Initially, though, it felt like they were trying to make you pity Hiroki, which is just bizarre.
At first, he even seemed like a victim too, but by chapter 4 or 5, it’s clearly shown that he brings a friend along to assault her as well, just so he wouldn’t be the only one to take the blame. And yet, the author keeps trying to make you sympathize with this character, which is honestly disturbing. It’s almost like the abuse and torture the girl suffers are just treated as background noise, while the main focus is on the mental breakdown of one of the people responsible for it. Knowing it’s based on a real case makes it even more disgusting.
When the story focuses on the sister, it gets way more interesting, and I honestly think it would’ve been better if it had been that way from the start. Or at least, if Hiroki’s perspective in the beginning didn’t try to sell any sympathy for him, but instead showed him through the victim’s eyes—just another one of the people responsible for her suffering.
If it were purely fictional, that’d be one thing, but as I mentioned, it’s based on a real case, and treating one of the culprits (who is shown to be incredibly selfish) as a victim just feels disrespectful. They try to address this at the end, with Miki calling him a coward and that implies that he carries that guilt, but even so, it doesn’t come close to the pain the victim endured, which I feel could’ve been explored much more.
Her thoughts or feelings were never really expressed. Sure, from her expressions alone, you can tell she was dissociating or something similar, but they end up portraying her almost like a doll—just as the criminals treated her—which is really sad. We get more of their perspective on the case than hers.