Mr Queen (korean version) or Go Princess Go (Chinese original version)
Beauty Inside (movie) and Beauty Inside (series) => I personally find the movie a lot better but then I did watch that before the series came out so I might be based there.
If you read manga I'd actually recommend you to try "Kanojo ni Naru hi". This is the story about a world where the gender of people changes depending on the amount of people living, meaning if there are too many males than some kids end up change to the other gender. The story is about 2 guy best friends where one of them becomes a woman and how their relationship changes because of that. It really sounds absolutely weird but it is an amazing story, very well written.
The manga is completed and has only around 20 chapters.
There is also a spin off called "Kanojo ni Naru hi: Another", which follows 2 other characters, also well done but not as good as the original.
