Looking for a masked emperor/king manga

Cant find this one and its annoying since my memory of it isnt the best.
Maincharacter is a girl. Somehow she get hired in the palace. Medical apprentice or something.
The emperor is masked and has a hidden identity. Think is due to assasination attempts. Seriously cold blooded dude.
Think he even had some not so nice nickname. Other than that I remember some flirty general and a white haired dude. At some point I think I suspected the general being the emperor.....

Please help........