The Bride & the Exorcist Knight v01-v04 (2018-2019) Complete

English translation of the Japanese manga Hanayome to Futsuma no Kishi (花嫁と祓魔の騎士).
When Anne was born, it was prophesied that someday the demon Mephisto would claim her as his bride. When the day arrives, Anne is saved by a 12-year-old boy exorcist named Haru. Her salvation comes at a price, however: Haru wants Anne to marry him instead! Anne is not keen on getting engaged to a headstrong little kid, but if she wants to stay out of Mephisto's clutches, she may have no choice.