Hiei was born in the island of the Koorimes,he was born from theunion of the ice maiden Hina and an unknown fire demon.Since he was male and part fire demon the other ice maidens ordered for him to be tossed of the floating island and left to die in the cruel world below. Before they threw him off the island, Rui, a friend of his mother, gave him a hiruiseki stone that his mother cried while giving birth. She also gave him permission that if he ever survived, he could come back and take his revenge on them. Hiei did survive and was brought up by a ring of demon theives. He became an A-class demon because he was so powerful the theives were afraid of him and he was abandoned once more. Later, he got a Jagan eye implanted so he could find his twin sister Yukina.

The Jagan is a third eye that allows the used to control minor demons and summon immense powers. The demon Shigure implanted it for Hiei, under one condition of course:: Hiei could never tell Yukina he was her brother. The Jagan implantation almost killed him, lowering him down to a lower D class(the weakest of demons).Using his Jagan, he found the island of koorime and met Rui. She told him that his sister had left the island few years ago in search of her brother. Even though he had permission to eliminate the Koorime race, he left the island once more to continue his search for his sister.

At the end of the series Hiei goes to Makai as Mukuro's heir.