ʻUmi-a-Līloa (fifteenth century) was a ruling ali'i-ai-moku (district high chief of Hawai'i) who inherited religious authority of Hawai'i from his father, High Chief Liloa, whose line is traced, unbroken to Hawaiian "creation". His mother was Akahi. She was of a lesser line of chiefs who Liloa had fallen in love with when he discovered her bathing in a river. He became Chief after the death of his half-brother Hākau, who inherited the lands of his father to rule. Umi-a-Liloa was considered a just ruler, religious and the first to unite almost all of the Big Island. The legend of Umi is one of the most popular hero sagas in Hawaiian history. While there is probably embellishment to the story, as many sagas do, a portion of historic accuracy remains.
ʻUmiʻs wife was Princess Piʻikea, daughter of Piʻilani. Piʻikea and ʻUmi were the parents of son Kumalae and daughter Aihākōkō.
His father was Ali'i-ai-moku Liloa, and his mother, Akahiakuleana (Akahi). Each were married to another. The couple met when Liloa, the then ali'i-ai-moku of Hawaii was visiting the local area of Hamakua. He met Akahi there and claimed his right to her as King and she accepted. After they had consummated, Liloa told her that, if she was to have a male child, she should present the boy to him along with royal tokens he gave to her as gifts, to prove her boy was the son of the king. Akahi hid the gifts given to her by Liloa from her husband and later gave birth to a son. At the age of 15 or 16, his step father was punishing the boy when his mother intervened and told the man he could not touch him because the boy was his lord and chief. She recovered the hidden tokens of royal sovereignty to present to her husband to prove the high treason he would have committed. Akahi gave her son the gifts of the royal malo and lei niho palaoa which were given to her by his true father, that only the high chiefs wore, and sent Umi to Waipio to present himself to the king as his son.
Liloa's palace was well guarded and attended by several Kahuna. The entire enclosure was sacred and a penalty of death stood for breaching its walls. Umi entered the walled off enclosure with attendants afraid to stop someone wearing the royal insignia and walked straight to Liloa's sleeping quarters, waking the king. When Liloa asked who he was, he said "It is I, Umi your son". He then placed the tokens at his fathers feet and was proclaimed son by King Liloa. After learning of Umi, Hākau became upset and demanded answers from his father, who assured his first born that he would be king after his death and his brother would serve him. Umi was brought to court on an equal footing with his half brother Hākau, who was the son of Liloa with his first wife, Pinea from an ali'i family of equal rank to that of her husband. Living within Liloa's court alongside his brother, Umi found great favor from his father, only increasing Hākau's dislike of his half brother.