Mei, a fifteen-year-old rebel with the Returners, fights oppressive regimes inside the domed cities. She flees Datania alongside the protagonists, seeking refuge in Amaroute. During their journey, she fiercely protects Shu, embracing him as a younger sibling. Her allegiance to the Returners embroils her in the hunt for DT, a rare substance within specific humans, placing her directly against pursuing antagonists.