( chapter 3:refused to see her but also didn't go back to college because she knew Aya would contact her eventually.
chapter 4:......damn this woman.
chapter 7:bought her a smartphone and let her find a part-time job as her wish. Knowing there's no possibility she would get hired. By doing this, Aya will acknowledge she can't live without her now.)
I don't feel like are reading the same manga... Whether it's Koto or Erika, I feel like people are really hard with them, and I don't think this is the way Kabocha wants her characters to be portrayed.
The only thing that could make we feel Koto is manipulative, was she when was shown with the manuscript on a stage. But that was more for the dramatic effect more than anything else I think (Kabocha seems to enjoy giving a bit of a creepy feeling at the end of each volume).
I think Koto just had a strong PTSD because of Aya's disappearance and has difficulties whenever she cannot control the situation. Yet, she has never hinder Aya in any way. She lodge her, pay for her expenses and don't ask much in return. She does have issues to be addressed for sure, and she does have a problem expressing herself. I bet that she was so closed off for many years, that even Aya's reappearance was not enough to trigger her coming out of her shell. And it's totally logic in a way. Aya disappeared magically, why wouldn't she disappeared again the same way?
Same goes for Erika. Her internal dialogue is quite harsh, but regardless of what she is thinking, her actions speaks for herself and she is giving good advice and helping Aya. I do think when cares about her, but she is conflicted about the fact that Koto can't let her go. Her jealousy is probably triggering those bad though, but in all honesty, she is being a good friends and is doing more good than what her internal dialogue is suggesting.
I'm not saying those characters are perfects, far from that. But I feel like the story is more about Erika and Koto resolving their personal issues, rather than it is about Aya finding her way. She is honestly doing fine and is the more adult of the three...