Lucifero, the current Devil King, announces his retirement and forces his reluctant descendant Osamu into a deadly succession contest. Ambitious demon cadets flood the human world, each determined to claim the throne by collecting powerful familiars born from human souls. Osamu, however, couldn't care less about infernal politics or world-shaking prophecies. He'd rather stock shelves at his convenience store job than play along with his family's schemes. Forced to compete whether he likes it or not, Osamu stumbles through the competition with zero enthusiasm, collecting familiars at a snail's pace while his rivals grow stronger and more ruthless. The core tension sits between supernatural stakes that demand his attention and his stubborn refusal to treat any of it seriously. His apathy becomes both his greatest weakness and potentially his unexpected advantage in a game where ambition and desperation cloud judgment. This supernatural action story balances high-stakes demon politics with the mundane absurdity of someone who just wants to keep his retail job. It appeals to anyone who enjoys characters resisting grandiose destiny with sheer indifference.