When Aang visited the Spirit World seeking the help of Tui and La to save the Northern Water Tribe, he disturbed a baboon spirit's meditation. A firefly passed by and the spirit suggested that Aang follow it, as it might lead him to what he was looking for. It led Aang to Avatar Roku, who told him about the spirit, Koh. Months later, while in a coma after being struck in the back with Azula's lightning, Aang was tasked with catching multiple Spirit World fireflies and placing them in a lantern. Once he completed the task, Roku's animal guide, Fang, appeared and guided him to Avatar Roku.