Tulip Prison—a special penitentiary filled with criminals from all over Japan who have been deemed too far gone to rehabilitate. As the "phantom precinct" of the justice system, its facilities occupy an inescapable island that stands alone on the open sea. Amid the Christmas lighting one beautiful winter night, Shuichiro Minato was arrested—

In this world of humans fearful of the increasing number of monsters, the undeniable whisperings that the Demon King has returned are spreading... The thief Batz, who thinks he is the center of the universe, pays these rumors no mind as he lives his life as usual, stealing anything he wishes to. One day, while on his way to a bandit’s hideout--

Ryuuji Hirasaka. A depraved doctor with severe personality issues. Despite his genius, he has no interest in anything but humiliating and toying with other people, whom he views as nothing more than experimental subjects.