Zense ga Densetsu no Daimajo datta Fuguu Seijo wa Koutei Heika ni Dekiai sareteimasu

"Rejoice! I, the Emperor, shall make you my bride!" Orphaned and mistreated by her relatives, Sumire Inazuma never expected her life to change—until she and her cruel cousin Botan are suddenly summoned to another world as "Saints of Salvation." But when the Emperor Carlyle appears, it's not the lovely, manipulative Botan he proposes to—it's Sumire. Why her? And what is this mysterious, powerful bond that seems to link them across lifetimes? (Source: Kadokawa, translated)