This school is funded by Kagaritsuki family. Yuki is the youngest child of Kagaritsuki 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 drinks Chiyo's blood. Why does she give her blood to someone that she hates? Is there any secret between those two?

(Source: Shogakukan, Chibi Manga)