While volunteering in a war-torn country, I heroically sacrificed myself to shield a patient, only to awaken in a child's body in a strange world. Surrounded by unfamiliar faces and a wrecked carriage, I realize I've entered the realm of 'The Supreme Demon King,' a beloved Murim novel. Embracing my newfound role, I aid the 'Three Great Doctors' in saving lives, including the novel's protagonist, the future Demon King 'Yeoharyun.' Bound by gratitude, Yeoharyun insists on the title of 'hyung,' marking the start of our brotherly bond. Under the guidance of the wise Baekrineuison, I hone my skills and rise to become the most skilled healer in Gangho. This is the tale of my journey to greatness as a physician in a fantastical world.