Following the most intense battle of his life, a young man washes up on a strange shore. He is found by a swordswoman named Shizuka Kosugaya and informed that his name is Kojou Akatsuki, and that he is the fourth vampire primogenitor. In the days spent healing his mind and body, the two encounter a third person: A beautiful girl wielding a silver spear that calls Kojou… Senpai.