Hiei was born to an ice maiden named Hina when she was impregnated by a fire demon. Due to men being forbidden in the tribe, he was cast off their land to die. Before he was banished, his mother gave him a jewel that came from her tears. Hiei was then found by bandits and was raised by them. When he was grown he had the Jagan eye implanted in his forehead so he could find the Ice Maiden's mountain. He made it to the ice maidens' land to enact his vengence, but he let them live seeing how terrible their lives were. He then learns he has a younger twin sister who left the land to find her brother. He leaves the village, hoping to find her. He then uses the Jagan to watch over Yukina but is sworn to never tell her he is her brother.
When Hiei is first introduced, he had stolen one of three objects from the vault of the Spirit World, the Conjuring Blade, which has the power to turn humans into demons. Yusuke deafeats him by using his spirit gun and hitting the mirror of darkness,which bounces the spirit gun at Hiei, knocking him out.
He is then sentenced to aid Yusuke and Kuwabara to fight the Four Saint Beasts, killing the second-most powerful memeber, Seiryu, with no effort.
When Yukina is captured by Tarukane, Hiei races to save her, making it to Tarukane's room before Yusuke and Kuwabara. Seeing how upset the man had made Yukina, Hiei beats the man to near death and only stopped when Yukina begged him to spare Tarukane's life. Hiei lets the man live and joins the Dark Tournament, killing the most opponents.