I have been trying to remember a picture book I read to my children back in the mid 1990s. My son now has a child and wants to find that book. I am pretty sure it is a Japanese folk tale ( but maybe Chinese?) .  The story is  about a deformed scholar who is hired to tutor the beautiful young daughter of an important rich person.  There is a myth that before a baby is born, they know the person who they are matched to be with, their “soul mate”. But before a baby is born one of the angels will press a finger to the middle of the upper lip ( hence the dent in our lips)  causing the baby to forget all memories of this person.  then they search during their lives for that one person.
Apparently in heaven before birth, the deformed scholar was a handsome baby and the young girl was the one with deformities . For some reason… ones I cannot remember, he switches with her so she will be beautiful and he will carry her deformities. They end up falling in love down on earth. This was such a lovely book that both my children remember even 20+ yrs later