Afembe is a gender identity in which one is between male and female, but also neither, but mostly connected to femininity/womanhood.
No flag but anyone is free to make one.
Edit: for anyone confused, the be part is short for between, between meaning between male and female.
I also made a more desaturated one if you like-
Pink for femininity, blue for masculinity, green for neither 
Uhm so you don’t have to use this btw