"Plains of Eternity"(悠久の大平原, Yūkyū no Daiheigen?) is the main background theme of the Archylte Steppe in Final Fantasy XIII-2. It is composed by Naoshi Mizuta with vocals by Joelle and mixed by GOH HOTODA. Its non-lyrical counterpart, "Plains of Eternity -Aggressive Mix-" (悠久の大平原-Aggressive Mix-, Yūkyū no Daiheigen -Aggressive Mix-?) plays whenever enemies appear. The theme plays during sunny weather, which is the weather when Serah and Noel first arrive at the steppe.