Aquas Trussler is a bronze-rank adventurer who lives only for his hobbies and training, content with his simple life. Everything changes when Uiras, the Goddess of Creation, offers him an unexpected job: become the Demon King and oppose the strongest Demon King's army in history. The pay? Nothing more than minimum wage. Even so, Aquas accepts the offer, beginning the story of the most underpaid Demon King ever.