Suho is a high school student normal... But he leads a difficult life, because his parents aren't interested to him. Furthermore, he's waken up with mysterious injuries on the neck and wrist after a strange dream.
Elsewhere, the king of southern Fantasy world is facing to 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 Suho, whose blood is particularly sweet. When the dragon asks him to follow them, Suho accepts to escape to his miserable life. But there's a problem : the king hates boys. The dragon suggests dressing up in girl to Suho, hoping the king doesn't notice.