It's too early to judge yet, but based on previous work (Yuunagi Marbled) I suspect it is going to be a straightforward case of abuse.
I thought YN's ending was just a little bit too pat, and if anything Aki is going to be even more damaged than Mishio was. And dating a teacher as a student, especially (can we please remember this...?) a 13 year old, sounds like a Bad Idea. She might be best served by waiting for love until college and going to therapy.