A special vampire race transitions from male to female the more blood the suck. The process is not very good animated but at least it shows decent signs of change.
https://animeflv.net/ver/53322/mayon...ult-koumuin-14 On chapter 14 most of the change occurs 19:57
https://animeflv.net/ver/53323/mayon...ult-koumuin-15 on chapter 15 there is a brief scene where her hand becomes softer 8:14