First of all, I apologize because I know, my friend, that I really went overboard with what I said earlier. Going a bit straight to the point, you're right that their emotional connection has grown so much. Hinako already said that Shiori is the most important thing for her, and from there it already shows that Hinako knows she loves Shiori, because she even stood up for her when Azami spoke badly about her, and she didn’t say anything to the tanuki when she did the same to Miko (and that’s her best friend lol). I really feel these homey moments are now when closeness will happen.
The plot has moved forward, and it’s time to advance the relationship a bit too, which is why I also want intimate moments between the two. Answering the first point, in chapter 62, she said she no longer hates that Shiori was kind to her, so Hinako indirectly admitted that she did hate Shiori’s selfishness, but when she listened to her heart and they had the conversation on the beach, Hinako saw that Shiori’s feelings are genuine and I think that made her see that Shiori, despite having been selfish, did it out of love, and that made her realize that she truly loved her and see her differently. Also, let's be honest, she said she would still be friends with Miko when she found out she was a psychopathic murderous monster, so when you put it like that, Shiori doesn’t look that bad lol.
More than her blood ruining 2 lives, she understood that with Azami it was a desire to live, a kind act with selfishness, but with a desire to do a good deed. Hinako saw it that way because she even said that although neither she nor Azami could appreciate Shiori’s kindness, at least with Hinako the blood was before the accident, so there really isn’t pure selfishness in making her live. That’s why Hinako stopped seeing it as something bad when she saw that Shiori did everything for Hinako out of love and not pure selfishness. Hinako, at some point, acts cruelly toward Shiori; she didn’t need to hate her because just knowing she was going to eat her was enough for her.
She needed to hate her because just knowing she was going to be eaten was enough for her, and you can see that when they go to their parents' grave. Hinako didn’t care about Shiori except for the promise of reuniting her with her family, but upon realizing that Shiori truly loved her, she stopped just seeking to die and yearning for her parents, but she also understood that she loves Shiori and that’s why she apologizes to her. I really hope these homey chapters do well for their relationship—they deserve it, and now that Hinako has admitted that Shiori is the most important, it’s time for her to show it. Lastly, something unrelated to this: I don’t think Shiori is going to investigate Erica too much.
When she delivered the blow, Shiori noticed something and said: it must be her, maybe she realized what she was the moment she touched her, and knowing Azami it’s likely she’s a yokai from Japanese folklore with just magic or maybe a counter to mermaids or an enemy since she hates her so much to have something just for Shiori and it explains because Azami said that Miko was an annoying element, maybe Erica is a yokai that's good against Shiori but not against anyone else.