A demon who is after Sakura. Later in the manga, it is revealed that he is Sakura's "dead" brother, Kai. Kai wanted to be a scholar but was betrayed when he entered the castle. He was trapped by emperor in a water tank as an insurance that Sakura would not betray human kind. After being drowned in the water for 5 years, he went berserk with the thought of Sakura being used by humans and escaped. He is gentle, but can also be cruel (never to Sakura).