The story begins with Valvatos, the former Demon Lord, reflecting on his millennia-long life spent fighting gods and their followers to liberate humanity. This relentless struggle led to him being feared and isolated, earning him the moniker "Demon Lord." His ultimate wish became to experience a genuine defeat, hoping it would make people see him as human again. However, no one was strong enough to defeat him. Facing a life of eternal loneliness, Valvatos created a reincarnation spell, leaving behind a will for his subordinates and activating it.
He is reborn as Ard Meteor, an average human in a distant future, approximately three thousand years after his previous life. The world has fragmented into numerous nations after his death, but has found a semblance of peace, though demons and "Outer Ones" (now called "Evil Gods") still pose a threat. Ard spends his early years, from infancy to age twelve, diligently acquiring language and increasing his magic power, immersing himself in the knowledge of this new era. He lives with his kind and ordinary parents, Jack and Carla, in a simple wooden house. Despite his desire for friends, a consequence of his past life and a newfound fear of others, he struggles to connect with people. His attempts to seek advice from his parents yield absurd results, prompting him to consult their friend, an elf named Weiss, who suggests a gentlemanly approach. Ard tries this, but his refined demeanor is perceived as strange and off-putting by his peers.
At age fourteen, Ard's life takes a turn when he hears a scream and teleports to find a young, silver-haired elf girl, Irina, being threatened by a large wolf. Ard effortlessly defeats the wolf with a single, un-chanted spell, astonishing Irina, who mistakenly identifies it as a powerful "Mega Flare." This encounter marks the beginning of Ard's first true friendship. Irina, impressed by his power and kindness, declares him her "first friend." Ard, overjoyed at finally achieving his goal, finds immense happiness in his friendship with Irina, his loneliness fading.
Ard's father, Jack, a blacksmith, brings home a new sword, but Ard, possessing his former knowledge, points out its flaws and enhances it with powerful enchantments. This reveals Ard's extraordinary talent, even to his parents, who are revealed to be the legendary Archmage and Hero Baron. Ard, however, wishes to remain ordinary, fearing the loneliness that comes with being special.
Ard and Irina are accepted into the prestigious Lairville National Magic Academy. During their entrance ceremony, their parents' heroic status is revealed, causing a stir. Ard's exceptional performance on the entrance exam, where his "incorrect" answers were actually revolutionary magical theories, earns him the title of genius and a place as the top student, much to his dismay. He is also recognized by Jessica, a young, talented instructor, and Olivia, a former trusted subordinate of Valvatos, now a formidable instructor herself. Olivia becomes suspicious of Ard's unusual abilities and knowledge, sensing a familiarity in his magic.
Ard's academic life is marked by his extraordinary talent, which consistently surpasses the current era's understanding of magic. He develops "Script Magic," a technique allowing for un-chanted spellcasting with zero mana consumption, and further enhances it. He also inadvertently creates a potion equivalent to the legendary "Sage's Elixir," further fueling Olivia's suspicions. He befriends a shy succubus named Jinny, whom he helps overcome her insecurities and develop her own magical abilities. During a dungeon exploration, Ard's true power is revealed when he effortlessly defeats a Minotaur, demonstrating advanced techniques and a profound understanding of magic far beyond the current era's capabilities. Olivia, recognizing these "lost skills," becomes convinced Ard is more than he appears, suspecting he might be the reincarnated Demon Lord Valvatos. Despite Ard's attempts to downplay his abilities and maintain his ordinary facade, his actions continue to draw attention and suspicion, particularly from Olivia, who begins to question his true identity.
