Chocolate Vampireチョコレート・ヴァンパイア; 초콜릿 뱀파이어

From Chibi Manga: This school is funded by Kagari Ritsuki family. Yuki is the youngest child of Kagari Ritsuki brothers, and and idol in the school. On the other hand, Kashiwagi Chiyo hates Yuki… The truth is Yuki is a vampire, and he always drink Chiyo’s blood. Why does she give her blood to someone that she hates? Is there any secret between those two?