Azuki's first sexual experience that wasbranded "disgusting", and evidently traumatized her. Yakou doesn't look at her or other girls that way. That's pretty ace if you ask me.
I don't know, it definitely seems like she has a sexual urge, with how she got off almost to completion with that figuring. Judging by that and her reaction after, I feel like her case is one of a deeply repressed sexuality that is most definitely caused by some intense trauma.
Not that asexuality is the point or even related to this manga necessarily, but I just wanted to say that the typically definition of asexuality is a lack of sexual attraction to other people, which means that regardless of whether a person masturbates or has a high sexual drive, they can still be asexual if they don't have the desire to have sex with other people. Based on Yakou's self description, I would call her asexual. But we still don't know if she is being completely honest, or if she's instead lying out of a sense of shame. In either case, I think it will be really interesting to see how this plays out.
