Black Bird, Complete Box Set, Volumes 1-18 (by Kanoko Sakurakouji)

There is a world of myth and magic that intersects ours, and only a special few can see it. Misao Harada is one such person, and she wants nothing to do with magical realms. She just wants to have a normal high school life and maybe get a boyfriend. But she is the bride of demon prophecy, and her blood grants incredible powers, her flesh immortality. Now the demon realm is fighting over the right to her hand...or her life!