This is a very touchy subject purely because it's "taboo" and society has ingrained us all to think in a certain way. For a manga to tackle this issue in such a direct and honest fashion is difficult, and the author has my greatest respect for it.
I know I'm gonna get bombed for this, but one of the reasons this manga is significant to me is that I've been in this situation, albeit a little closer in the ages, but the principal was the same. Now currently married with a family (as is my sister...to someone else 😛 ), having come out the other end of that issue in a different fashion than Koshiro has. Although having gone through similar self-doubt and guilt we see here in this manga. Taboo or not, we're human and things will happen around us and to us, and to be honest to one's self is what should matter most, not what society thinks is best. Makes me wonder if the author has similar experience and is trying to reach out to others.
It was nice not to have to sit through another 'magical' change of personality to get things moving in this story, but rather to let time tell it's tale, making this feel all the more real to read. Artistically, I agree with previous posters that the physical differences are bit overdone, though. It almost seems like they were being put into archetypical roles, with him being large and intimidating, and her being small and a bit overly child-like. Aside from that, the art was nice without being too sketchy or distracting, with the significant moments having a wonderful level of detail.
Top-notch realistic storytelling and worth a read even if the topic isn't quite your normal 'cup of tea'. Just about the right length, too...not too short to seem rushed, and not too long to seem like you can't wait for it to end
Took a little off in the rating due to character art, but every other aspect is wonderful