Underrated shoujo ai manga! The romance progresses very slowly though so if you're looking for a short and quick love story, this one might not be the one for you. However, if you want to read a long, mature romance with realistic relationships this one's definetely worth reading!
The main and side characters are all well written and you can understand every of their actions, often also due to background/side stories. Their actions are very suitable to their age. They are adults and they act like adults do and that's fairly impressive writing.
One thing though: The story has some issues, for example in the first chapter
Nanami splits up with her boyfriend which I think should've happened later so we first get to see how Kae and her realtionship to one another is. There's also not very much happening so far, there are a few arguments here, a few problems there, but it's hard to really tell what actually happens and how the characters develop. I'd recommend it to "advanced" manga readers, I wouldn't consider it very suitable for beginners