if Shizuka isn't proven to be pretending to be a nice girl to Hebikawa she will have to confront the fact that she's actually just a rotten person.
When Hebikawa first met Kusunoki, she was surprised when Kusunoki reacted differently to an embarrassing moment and was instead honest and direct about her feelings.
Hebikawa then remarked about how Kusunoki was how Hebikawa
wanted to be, when she was younger.
Hebikawa tried to be a good person who was mindful of others and polite and kind to everyone, and she got hurt and ostracized for it by her peers back in grade school -- but unlike Kusunoki, she instead became spiteful and mean and manipulative, all the while lamenting that she was getting "further and further away" from the ideal she had tried so hard to reach.
It's why when Keisuke tries to call her out for not being a good person, she agrees with him. She's the first person to say she's not a good person, but she's just stuck in this mode now, and has had no reason to grow past it, convinced that everyone "perfect" is secretly like her, and just hiding it.
Hebikawa & Kusunoki are mirrors of one another. Right down to the fact that Hebikawa is being proactive, whereas Kusunoki is being completely passive and avoidant in this current stretch of story. They both had bad shit happen in childhood, but Hebikawa 'broke' over it, whereas Kusunoki pulled back and inward instead.
Kusunoki lucked out in convincing Keisuke to help her out, and in so doing has turned the corner on her desire to "reinvent herself" and regain friendships and a sense of belonging. Hebikawa never had that, choosing to push everyone away and use them instead of letting them in.
Now that she's going after Keisuke toward her own ends, the opportunity for Keisuke to do for her, what he did for Kusunoki, has arisen. He already "sees through her", and she's already shifted her perspective a touch when it comes to him after he helped her with her dad and on her birthday.
Which is why I maintain that I think it's likely that Hebikawa
will get some form of 'redemption', wherein Keisuke helps her like he did Kusunoki, and shows her that it's not that "perfect people are fake and hide their darkness", but that
everyone struggles, and that it's how you react that determines what kind of person you are. If he helps her see that, then she might get to the point where she mellows out, tries to be more honest and authentic, and can build meaningful relationships again.
And in the meantime, Hebikawa serves as a foil to Kusunoki, who is very much romance-averse, and creates the potential for Kusunoki to be more honest about
her feelings, especially toward Keisuke, in turn.
Hebikawa's the antagonist of the story, but I don't think she's an irredeemable one, much less a "one-note" one, agreed.
