Yui's vampire sister
A name that almost no one knew about. Kyuketsuki is a shy, kind, self-less, generous, beautiful, vampire. Yes. Vampire. Yui despised her sister, but kyuketsuki understood, and never really hated her sister for that. She knew that no one would want to be friends with her and she was alone. Now let's see how a vampire with the most irresistible blood and most beautiful looks can survive the sakamaki brothers.
Disclaimer: the diabolical lovers anime does not belong to me. Only kyuketsuki and the plot is.