Well, we made it all the way to the end of volume one, and I'm still really not sure whether or not it's actually teacher/student. On one hand, there are four main characters, and by yuri logic, that must mean two couples. On the other hand, I feel like this chapter shows that Yuna's feelings are just idolization, not actually attraction, and it also seems to set up a personal arc Shiratori outside of her relationship to Yuna. Personally, I'm really hoping this series doesn't go in a teacher/student direction, but I might just be seeing what I want to see. Either way, I think the treatment of Yuna's feelings, both by the story and the characters, is pretty interesting.
I wonder about the possibility of Hotaru/Shiritori. It seems like most people are assuming that Hotaru and Aki are in a happy relationship, or want to be in a happy relationship but something is holding them back, but I wonder if that's not the case. All the flashbacks are, at least to me, tinged with a sense of melancholy, and the series is constantly emphasizing Aki's absence. I wonder if maybe they used to have something, but their relationship has turned stagnant over time, and that's why Aki is away all the time. I find it interesting that the last page of the last chapter of volume one is a spread of Hotaru wanting to reach out to Shiritori, but not being able to. I'm not betting on this interpretation, but I think it's interesting to consider at least.
Thank you for the TL!