From [url=https://www.mangaupdates.com/series.html?id=1750]Baka-Updates Manga[/url]:
Ryuunosuke's from an impressive clan... Or well, his secret is impressive, but he's not. After receiving a an unknown vampire doll from his sempai, his spilled blood wakes it up. With the soon-after death of his dear colleague, he also acquires a beautiful meat-eating girl. These two girls guide Ryuunosuke in controlling the monster that lurks within his blood while he tries to figure out the true reason for his existence.