These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Darkness-Induced Audience Apathy: The narrative piles up so much trauma, woobieness and weepy melodrama on the reader that, at times, it can be quite the chore to read.
Iron Woobie: Hinako, while also being very vulnerable, does have a tinge of iron, starting from the first chapter when an oblivious Daisuke pushes her against the wall, intending to take her up on her "faux innocence" (as he thinks), and is shocked to find her staring right at him, as if resolving herself to some terrible fate. Considering what must be going through her mind, this is simply "Wow".
Whether this was intended is debatable, but there is some evidence as the story goes on that this is what's known as "learned helplessness": after being hurt so many times with no chance of escaping, it becomes a reflex to just surrender to the pain and not even look for a way out. This is made worse by the fact that for her struggling actually increased the pain. In this case, it must have taken incredible willpower to try and escape the attempted rapist in volume 2.
Values Dissonance: Things like Daisuke's sister's pregnancy and Hinako's history of being abused would be nowhere near as big a deal in Europe or America as they're depicted in this manga, so it's important for readers to remember that Japan is still struggling to shake off the whole Defiled Forever concept.
You can't really single out Japan for that, and the way the author depicts this subject doesn't necessarily mean it represents Japan's modern feelings on the issue, or the author's. It's just a story.
Since when, in any modern culture, has the sexual abuse of a minor to the point of pregnancy TWICE, ever not been a "big deal?"
It's a big deal, and being raped is not seen as "the woman's fault" in Japan. However, rape still carries of stigma of dilution or tarnishing, in that a woman has been - against her will or otherwise - ruined, and therefore an undesirable candidate for marriage. One does not blame a faulty product for being damaged by someone else, but ultimately people don't want a faulty product... or so Japanese traditionalists see it.
Fortunately it's not as if the story sees it that way. Kei Kusunoki is firmly on the side of her female characters.
Also, victim-blaming is noooot unique to Japan.
And concerning Daisuke's sister, a woman having an affair with a married man can still be a very divisive matter in many cultures, especially if she gets pregnant and decides to keep and raise the child regardless of the father's feelings.