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.
Ensemble Darkhorse: Original characters Ayaka Suzuki and Nanami Tanaka proved to be popular enough to justify them returning for the next fanfic, Holiday Vacation where they played a much bigger role.
Iron Woobie: Konata, ironically enough, qualifies. After all, the poor girl's been trying so hard to tell Kagami her true feelings towards her, but she hasn't succeeded for more than 3 years. And then she witnessed Kagami suffer the mother of all beatdowns at the hands of Sakura, after having a nightmare about it the previous night. But what does she do? She starts fighting back. Hard. Because of this (and the fact that she was also injured during the fight), she becomes a good example of this.
Another possible example of Sakura crossing the line is that when Kagami starts to cry after begging her to stop, Sakura responds by laughing at her, then slashing her with the knife again, and to top it off boasting that no one can save her now.
Nightmare Fuel: Everything about Sakura, but the worst thing about her is how horrifyingly realistic she is. Remember that brutal No-Holds-Barred Beatdown that she inflicted on Kagami? That kind of stuff actually happens in real life.
What an Idiot: Sakura really should have known better than to try to get even for something that wasn't worth getting even over. And at her trial she doesn't even make an attempt to try to defend herself, instead insisting that Kagami had it coming.
The Woobie: Kagami forobviousreasons and especially during Chapter 4 after Sakura inflicts the mother of all beatdowns on her. Seeing her sprawled out on the ground and crying her eyes out from the excruciating pain of her injuries, it's almost impossible not to feel at least a little bit sorry for her, especially if you thought she was already a Woobie in the main series.