One hundred years ago, humanity was driven to the brink of extinction by the sudden appearance of monstrous beings known as Fiends. Conventional weapons proved useless, forcing the remnants of civilization to splinter into seven fortified nations and develop military-grade magic technology. At the heart of this desperate struggle stands Alus Reigin, the world’s foremost Magicmaster and the sole holder of the top rank among the hundred thousand Magicmasters who protect humanity. Having fought on the front lines since the age of six, Alus has reclaimed more lost territory than any other soldier. At sixteen, he fulfills his military service and requests retirement, longing for a quiet, peaceful life. The governing authorities, however, refuse to lose their greatest weapon and strike a compromise: Alus may retire only if he enrolls as an ordinary student at the Second Magical Institute, concealing his identity and training promising young Magicmasters to become his successors.

At the academy, Alus struggles to blend in while secretly guiding his classmates. His first students are Tesfia Fable, a beautiful but sheltered noble girl who wields hereditary ice magic, and her gentle friend Alice Tilake, who possesses a rare magical affinity. Soon he is joined by Loki Leevahl, a girl he once saved from Fiends; she becomes his dedicated partner and uses lightning magic along with a talent for detecting monsters. Alus also catches the attention of the student council president, Felinella Socalent, a wind-magic user whose father is a high-ranking military officer, and reconnects with Leti, another top-ranked Magicmaster and an old friend who commands explosive fire magic.

Despite his efforts to remain unnoticed, Alus’s overwhelming power draws him into a series of escalating conflicts. He continues to fight Fiends in secret, protects the academy from attacks, and navigates political machinations among the noble families. Later arcs involve the aristocratic war game known as Tembram, where Tesfia risks her engagement and family honor with Alus as her mentor. As tensions rise, Alus is framed for murder and a magical terrorist attack, becoming an internationally wanted fugitive. Forced to flee into the outer wilderness with Loki, he must clear his name and uncover a conspiracy that threatens the fragile alliance of the seven nations. Through all the battles, conspiracies, and attempts to find peace, Alus remains a calm and pragmatic strategist, reluctantly accepting that his greatest challenge is not defeating monsters but escaping the role of humanity’s strongest protector.