Yumi is a sixteen year old girl, born on Kyoshi Island to the Kyoshi Warrior, Akira. The circumstances of Akira's pregnancy are unknown to Yumi, but the young girl always had almond shaped, hazel eyes, pale skin, sleek black hair, and a narrow face, the features found in people of the Fire Nation.

When she was eight years old, Akira was wounded by a fire bender. The wound became infected. A group of water tribe warriors came to Kyoshi Island and were willing to help her, but it was too late; Akira was going to die. Hakoda of the Water Tribe asked her if there was anything he could do for her and she simply asked him to take her daughter, Yumi, somewhere to be safe and loved. Naturally, he sent her back to his home to live with Kana, Katara, Sokka, and the rest of the tribe.

Unfortunately, as safe as Yumi was in the South Pole, she was not loved. The people judged her. Katara treated her as an enemy. She looked too Fire Nation for comfort. Katara felt betrayed that her father had helped Yumi and Akira, but he had left her and Sokka to go fight.

Yumi felt isolated. She spent much of her day writing poetry and blurbs. Some days, she would go fishing with Sokka and became rather skilled with the bow. When the young archer holds her bow, all the confidence in the world rushes to her. Yumi also has some skill with knives and carries a boot knife and a long dagger on her side. She had always wanted to learn how to be a great warrior like her mother, but the only other person in the South Pole with the same mentality was Sokka. There was no one to teach them.

Our story starts shortly after Katara found Aang in the ice berg. Yumi enjoyed Aang's company because he didn't judge her like everyone else did. He knew that having gold eyes didn't make her evil. Yumi hoped one day, he could bring the world to peace so that everyone could live without fear and prejudice. She hoped that within her lifetime, the war would end.