Let's get the elephant in the room some spotlight first:
1. Aya is 16 and Kuro is 24: Clearly, some people might-, no, will find a big problem with this. I have no arguments there.
2. There are some obsessive behavior triggers in this story as well: read at your own risk.
3. There are very erotic and sexual scenes: no comment on that.
Now that we're done with those disclaimers, on to my review.
I personally think this manga is very very good.
PLOT: The author really knows how to pull you into the plot without cheesy lines or cringy storylines. I think that's one of the things I really enjoyed while reading. The story itself is something you can see happening in real-life (which might be a problem for some people - because of Kuro seemingly being a pedophile - more on that later) which I thought was very impressive.
ART: The art style is very well done. It's very clean and consistent. I've read quite a lot of high school-related manga and this was done very very well. I don't know what else to say when it's good hahaha.
CHARACTERS: As aforementioned, Aya is 16 years old so having a relationship with an adult, is ethically and morally wrong. As I've said I have no arguments with this. It's just that during the story, you forget that Aya is just a 16-year-old. She is not your typical teenager and clearly is way more mature than a typical girl her age. It might be due to the fact that she reads a lot. Still, the way her thoughts are processed and her actions too, and even her looks, to be honest, is clearly more of a mature individual. As another reviewer mentioned, it might have been better if the author made Aya 18 years old from the start; and I don't think that would have affected the storyline much (besides the moral and ethical aspects of it being more acceptable (?))).
But despite that, if you're into Yuri or a story about trying to heal a broken heart that turned dark from exhaustion, I recommend this story.
It's a good read.