Mamono no Hanayome

Overview

"Will you give your virginity to a vampire!??" Hana Sumioka has dedicated her life to work and has never had time for a boyfriend. One day, after working too much overtime, she fell off the train platform. When she awakened, she found herself inside the world of a fairy tale she read when she was a child. Hana, alone and injured, is saved by Flora, the main character of the story. However, Flora's brother Nicholas kidnapped Hana to sacrifice her to a man-eating monster in Flora's place. When the vampire came to suck on her blood, Hana's body is overtaken by a sudden heat...? (Source: Bebe, translated)

Source: AniList