After a catastrophic epidemic wipes out adults on earth, vampires emerge to enslave the remaining human population. Yuichiro escapes captivity and joins the Japanese Imperial Demon Army. However, before he can fight vampires, he must complete his first, terrifying mission: make new friends with his fellow aspiring monster slayers!

Yuichiro and his friends are kept as vampire fodder in a creepy institution disguised as an orphanage. One day, Yuichiro's dreams of fighting back are realized when the orphans stage a daring escape. But things go horribly wrong, and his dream is kept alive at a cruel price.

In this post-apocalyptic world of vampires vs. humans, Yuichiro seeks vengeance upon his vampire overlords. His dream, though, is near-impossible, as vampires are seven times stronger than humans. The only way to kill them is by mastering Cursed Gear, advanced demon-possessed weaponry. Not to mention that humanity’s most elite Vampire Extermination Unit, the Moon Demon Company, wants nothing to do with Yuichiro unless he can prove he’s willing to work in a team—which is the last thing he wants!