Su-ho is a normal high school student... But he leads a difficult life, because his parents aren't interested to him. Furthermore, he's wakes up with mysterious injuries on the neck and wrist after a strange dream.

Elsewhere, the king of southern Fantasy world is facing a serious problem : lack of blood, which causes a drastic reduction of his fighting power. He must find humans and take their blood. Therefore, his servant and his dragon are looking for a human to satisfy their master.

They end up meeting Su-ho, who's blood is particularly sweet. When the dragon asks him to follow them, Su-ho accepts to escape his miserable life. But there's a problem: the king hates boys. The dragon suggests dressing up as a girl to Su-ho, hoping the king doesn't notice anything.