Hole—a dark, dilapidated, and chaotic district where the strong prey on the weak and death is commonplace—is hardly deserving of its name. A realm cut off from law and ethics, it serves as a testing ground for the magic users who dominate it. As a race occupying the highest rungs of their society, the magic users regard the denizens of Hole as nothing more than insects. Murdered, mutilated, and used as experiments without a second thought, the powerless Hole dwellers litter the halls of Hole's hospital on a daily basis. Possessing free access to and from the cesspool, and facing little challenge to their authority, the magic users appear indomitable to most—aside from a few. Caiman, more reptile than man, is one such individual. He hunts them on a heedless quest for answers with only a trusted pair of bayonets and his immunity to magic. Cursed by his appearance and tormented by nightmares, magic users are his only clue to restoring his life to normal. With his biggest obstacle being his stomach, his female companion Nikaidou, who runs the restaurant Hungry Bug, is his greatest ally.