"The Misfit of Demon King Academy" is set in a world where magic is a fundamental part of society, and the Demon King of Tyranny, Anos Voldigoad, reigns supreme. After growing weary of the endless wars between humans and demons, Anos sacrifices his life to bring peace, promising to reincarnate in the distant future. Two thousand years later, Anos is reborn into a world where his legacy has been distorted, and the demon race has grown weaker. Enrolling at the Demon King Academy, an institution designed to identify his reincarnation, Anos quickly discovers that the academy's methods and the demon society's understanding of history are flawed.

Anos is a prodigious figure, possessing immense magical power and knowledge far beyond that of his peers. Despite his overwhelming strength, he is labeled a "misfit" by the academy's rigid system, which fails to recognize his true identity. The story unfolds as Anos challenges the academy's hierarchy, confronts the misconceptions about his past, and seeks to uncover the truth behind the changes in demon society. Along the way, he forms alliances with key characters, including Misha Necron, a quiet and observant girl with a mysterious connection to the past, and Sasha Necron, her fiery and competitive twin sister. Both play significant roles in unraveling the mysteries surrounding Anos's reincarnation and the forces manipulating the demon world.

The narrative explores themes of power, identity, and the consequences of rewriting history. Anos's journey is marked by his interactions with various factions, including the Hero Academy, which represents humanity's side of the conflict, and the enigmatic Avos Dilhevia, a figure claiming to be the true Demon King. As Anos dismantles the false narratives and confronts those who seek to exploit the demon race's decline, the story delves into the complexities of leadership, loyalty, and the enduring impact of his original sacrifice. The series balances action, intrigue, and character development, presenting a layered tale of a legendary figure navigating a world that has forgotten his true legacy.