In the quest for forbidden knowledge «homo sapiens» screwed up again - in 2012 deadly virus broke out , which began destroying humanity. Somehow died only grown ups, and then, out of nowhere, vampires came and the remaining children were herded into their underground city, declaring that henceforth the "little people" live under the protection of fanged owners, paying blood. Sharp guy Hyakuya Yuuichirou lived since 4 years
and knew it was time to break out - along with his brother called Mika and the whole "family Hyakuya", a group of children who grew up in the same orphanage. Of course, vampires are easily caught up and killed the fugitives left only one.
Coming to the surface, young Hyakuya realized that the epidemic was over, but the world has changed - the terms of devastation, wandering demons, and gradually expand the territory of the bloodsuckers, offering residents a "roof". The authorities in Japan seized the Hiiragi family, formed the Imperial Demonic Army, which protects humans and hunts vampires with enchanted weapons. Yuuichirou knew that he has to get inside Imperial Demonic Army, to avenge dead relatives. Direct and gusty guy is met with a lot of surprises, but in this hell of a world it is better to hope on his own ability and his sword than the will of fate and favor of gods!