|"It's so cold, and I can't get warm!"|
|— Katara quoting Nini while telling a ghost story.|
Nini was a character in a ghost story Katara told to her friends. In the story, Nini lived in the Southern Water Tribe and was friends with a young Kya, but fell victim to a blizzard and was never seen again.
When Nini was a little girl, her village fell victim to a devastating blizzard that buried her entire house under snow for weeks. Her friend Kya realized a month later that she had not seen Nini since the storm, and went to visit her house with a few other villagers. When they did not find her or her family, the men went out to search. Kya remained in the house where she heard an ominous voice say, "It's so cold and I can't get warm!" She quickly recognized the voice as Nini's and turned to witness her standing by the fireplace trying to get warm. Her skin was blue, as if she were frozen. Kya rushed out of the house, but by the time help arrived, Nini was no longer there. Rumors persisted in the Southern Water Tribe that her house was haunted, and many villagers reported seeing smoke rising from the chimney of her house, as if Nini were still trying to warm herself by the fireplace.
- Nini is one of the few Water Tribe characters who does not have the schwa phoneme in her name.