Call me out if this seems like a misread but thus far up until this chapter we've only been allowed to see the bad of Koto while it's seems we've been given much more "fair/generous" for lack of a better looks into Aya and Erika in seeing their ups and downs. I get that ultimately she is the most problematic person in the series but on some level it feels like her development is back loaded compared to the other two.
It’s been a minute since my reread so I’m going off memory but I do believe you have a point worth discussing. I do think Koto has some good moments but they’re smaller slice of life moments like in the bonus chapters. Other than that, there haven’t been many opportunities where she showed her good sides, to the point I get why people question what the other two see in her.
i can’t bring myself to dislike her though, for the simple reason that I know I could easily become her if put in the exact same situation. Something I learned while playing Life is Strange, I’m not above making objectively immoral choices for someone special to me. For better or (probably) worse, she’s the character I relate to most so I probably cut her more slack than I should.
Unfortunately, I don’t see much improvement for Koto as things stand.
To have finally taken the next step to deepen her bond with Aya, then for her to suddenly just vanish, without any explanation, I can see why it ruined her. Without any closure, it was impossible for her to truly move, no matter how hard she tried. It’s like she gave a piece of her heart to Aya, only for both to vanish, leaving this hole that can never be filled.
Then Aya came back, but there was no explanation for why or how she disappeared, and more importantly, whether she’ll disappear again. That’s half the reason Koto wanted to keep Aya locked up in her apartment, if she doesn’t leave, she hopefully can’t disappear again. Without answers, it‘ll be difficult, if not impossible to settle Koto’s anxieties about whether Aya will disappear again.
Then there’s the anxieties regarding change. Koto tried to move on but couldn’t, and part of her still feels stuck as that same girl she was back in middle school, still in love with the Aya she knew back then. Meanwhile, present day Aya is trying to change at a fast pace, so Koto has anxieties about Aya leaving her behind or changing in a way that makes her unrecognisable from the girl she loved. On the flip side, Koto doesn’t want Aya to see the ways she‘s changed, especially the part where she tried to move on. If you think about it, from Aya’s perspective, it seemed like they’ve been in a relationship the entire time, so Koto fears it may be seen as being unfaithful.
That side of things is something they are starting to work on. Aya has acknowledged the problem and created distance between them precisely so they can get to know each other again. The ball is in Koto’s court on this one. Hopefully her other friends, who are not named Erika, can give her the push she needs to both open up about her past and face present day Aya.