Strike the Blood

Strike the Blood (ストライク・ザ・ブラッド, Sutoraiku za Buraddo), also known in short form as SutoBura (ストブラ), is a Japanese light novel series by Gakuto Mikumo with illustrations by Manyako. A manga adaptation began serialization in June 2012 in ASCII Media Works's Dengeki Daioh. A 24-episode television anime adaptation by Silver Link and Connect aired between October 4, 2013 and March 28, 2014 in Japan.

Plot
The Fourth Primogenitor is the world's strongest vampire that should only exist in legends, but he has emerged in Japan with twelve familiars to spread chaos. For the observation and obliteration of this fourth primogenitor, the government and Lion King Organization decided to dispatch an attack mage known as a Sword Shaman. For some reason, the one chosen for the observation was an apprentice Sword Shaman girl, Yukina Himeragi, who is just a middle-school girl!

Wielding the strongest anti-demon spirit spear, Yukina arrived at Demon District, Itogami Island to find the fourth primogenitor. When she finds him, she becomes confused about the true identity of the fourth primogenitor, Kojou Akatsuki. Not to mention the boy cannot remember how or why he is the fourth primogenitor!