Does anyone know the title of this story? In it, I remember there was a princess who wasn'...

Does anyone know the title of this story? In it, I remember there was a princess who wasn't first in line for the throne, but she was actually the reincarnation of some great king from the past. There are a certain number of knights she is supposed to gather. I believe that when she's knocked out she can appear in a room in her dreams where she speaks with her soul's previous incarnations. I believe one part of the story has an arc where she pretends to be her cousin or something who ran away from her wedding and she has to play that role while people search for the real bride. That's about all I can remember of it.