A brief summary of my thoughts is that, Kanojo ni Naru Hi isn't bad but it's not great either. Read it if you want, just don't take it too seriously.

With that out of the way, Kanojo ni Naru Hi is a manga that, more so then any other I've read, will vary depending on what you want this manga to be. Don't get what I mean, that's fine I'll try to elaborate.

The first thing you'll notice when you approach this manga is the premise, a guy spontaneously transforms into a girl and it's out of his, or her, control. After that it follows the misadventures of the guy who was best friends with the newly made female before she was a she. With this premise the first thing one might assume is that it's going to tackle gender issues, acceptance of oneself, and challenging common views on the two subjects.

But it really doesn't do that much. The manga portrays two sides, the side that thinks emergence is disgusting and the side that thinks it's fine. But neither side manages to portray their side outside of shallow emotional knee-jerk reactions.

In regards to the side that looks down on emergence, it's understandable the stance they take. Whether or not you support transgenderism or not, the reality is that it is a small subculture of human life. It's a foreign thing that very well may frighten or disgust people, especially if they have a preconceived notion of gender and sex. And on the other hand, if someone experiences transgenderism, or in the case of this manga 'emergence,' it's something that is outside of the individuals control. The individual likely didn't ask to be put in a position like they are in. And even if it was their choice, it is their choice and no one else should control their life.

See that previous paragraph is comprised of simple arguments for both sides that I came up with in maybe fifteen minutes, but the author couldn't manage to do the same in the entire publishing time. Instead of posing questions that challenges how people think on both sides of the issues the author goes down the path of "We should accept everyone," which is fine if that's what you want to read, but I was disappointed.

Instead when I look at it, and it's side story "Kanojo ni Naru Hi Another," both are much better read as stories about accepting oneself, especially Another. They both do decent jobs tackling how different individuals may feel, even if some of the romance is forced, and when read with that idea in your mind they're fun.

If you want to read something that better tackles the idea of sexual and gender identity, go read "Himegoto: Juukyuusai no Seifuku" or "Shimanami Tasogare." They tackle the previously mentioned ideas in real ways that help you understand what the characters face.

Other wise if you just want to read something that touches these issues on a surface level with average art but good character development, Kanojo ni Naru Hi is an alright pick.