In a world devastated by an enigmatic virus that seemingly leaves only children alive, these survivors find themselves enslaved by vampires. Among them is 12-year-old Yu, the protagonist, who resents being treated as livestock by his vampiric overlords. Contrarily, his best friend Mika appears to acquiesce to their demands, particularly those of Lord Ferid, a vampire noble, by allowing Ferid to consume his blood in exchange for provisions for himself and the other orphans at their residence.
Mika later reveals his true intentions: he has pilfered a map and a gun from Ferid's mansion, planning