Seraph of the End: Vampire Reign

According to legend, a "man-made" virus causes the end of the world in 2012, destroying most of the planet's population and sparing only young children under the age of thirteen. The vampires emerge from the earth's depths at the same time, possibly followed by legendary ancient dark creatures. The survivors of humanity are subjugated and led below the surface to safety as they violently sweep the land and claim it. They must "donate" blood to their captors in order to receive this "protection," unaware that their captors are vampires. At the age of twelve, Yichir and his buddy and fellow orphan Mikaela hatched a plan to leave the Hyakuya Orphanage with the other kids. Mikaela sacrifices himself so that Yichir can escape and be saved by men of the Moon Demon Company, an extermination unit of the Japanese Imperial Demon Army, however this led to their deaths. Four years later, Yichir commits his life to eradicating vampires and exacting retribution on them for the murder of his "family." At the same time, it is made known that Mikaela is still alive and has intentions to track down Yichir.