Ei's Chosen

Awoken with no recollection of how he ended up on Serei Island, Relon and his younger sister, Qiqi, are thrown into a world where the elemental regions are at war with one another. Relon's only question; how did all of this happen and does no one want peace? Qiqi's only question; why are these girls falling for her big brother? AU. OC x Harem (Ganyu, Ayaka, Eula, Sara, & Baal).