The ultimate violent action that has surpassed 850,000 copies sold!! There is no way to stop the god of demons without substance that lives through the ages—at the scene of a series of murders where swordsmen are being killed one after another, a handwritten letter was left behind. The handwriting was strikingly similar to that of a genius female swordsman who has been missing for several years... What Kuroko, who is investigating the case, found was a locked, unopened storehouse. And then... the lid of the cauldron of hell was opened—The first volume of the spin-off "Murcielago BYPRODUCT -Arania-" featuring the popular character Reiko Kuchiba from "Murcielago" is also being released simultaneously!