Ummi was a Southern Water Tribe woman who fell in love with AvatarKuruk and intended to marry him. However, before the wedding ceremony could commence, Koh the Face Stealer dragged her into the Spirit World where he stole her face.
During the New Moon Celebration, Ummi met Avatar Kuruk. The two immediately fell in love and began a relationship. Kuruk soon proposed to Ummi with a betrothal necklace. The two were to be married at the Spirit Oasis in the Northern Water Tribe. However, as she crossed the bridge, she was pulled by an unseen force into the water. Kuruk jumped in after her, but could not rescue her in time. Koh, a spirit, had lured and trapped her forever to punish Kuruk for his arrogance.
Centuries later, when Avatar Aang entered the Spirit World, he confronted Koh and saw Ummi's face. Several months after that, Aang encountered Kuruk while in a coma and told him that Koh still had Ummi's face. Kuruk then vowed that he would keep hunting Koh until he and Ummi were reunited once again. He found the spirit and had every intention of destroying him, but could not when he realized that destroying Koh also meant destroying the love of his life.