Hiei is a Forbidden Child of the koorime (ice demon). When he was born, he was thrown off the koorime island and was supposed to have perished. Somehow, he survived, and he first showed up in yu yu hakusho because he stole something from the Reikai treasury. He was defeated by Yusuke he fought along with Yusuke, Kuwabara, and Kurama. He has a sister, Yukina, whom he is very protective of.