Hanayome to Futsuma no Kishi

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.