Mahiru Shirota dislikes difficult things, preferring to live a simple life. But after rescuing a cat he names Kuro, life takes a turn for the complex. Kuro turns out to be a “Servamp”—a servant vampire—named Sleepy Ash, and the two form a contract. Kissing his simple life goodbye, Mahiru is pulled into the world of vampires, the seven deadly Servamps, and war. Life couldn't be more complicated!