The Legend of Korra, Book One: Air

Opening:
"Earth. Fire. Air. Water. When I was a boy, my father, Avatar Aang, told me the story how he and his friends heroically ended the Hundred Year War. Avatar Aang and Fire Lord Zuko transformed the Fire Nation colonies into the United Republic of Nations, a society where benders and non-benders from all over the world could live and thrive together in peace and harmony. They named the capitol of this great land Republic City. Avatar Aang accomplished many remarkable things in his life, but sadly, his time in this world came to an end. And like the cycle of the seasons, the cycle of the Avatar began anew."