You and Yui went to a place where your father told you and Yui to live there, but your father trapped you and Yui. It turned out that your father sacrificed you and Yui to become the prey of a vampire family named sakamaki. Yui were terrified when you and her found out they were vampires

Laito: "well well well, who do we got here? Some delicious 2 human girls."