Chapters 3 through 12 of the light novel detail the initial stages of protagonist Lewis Alzeid's journey as he navigates a world rife with political intrigue and ancient conspiracies. Lewis, a forty-year-old E-rank adventurer, possesses the seemingly invincible skill "Unconditional Victory," a power whose origins are slowly unveiled. He is accompanied by Alicia Carfey, a magically gifted but equally weak mage, who is determined to improve alongside him.
The narrative begins with Lewis and Alicia facing a massive monster attack on the capital of the Saxendria Empire. In a moment of desperation, Lewis awakens his "Unconditional Victory" skill, effortlessly defeating the monsters. This feat earns him an offer of S-rank promotion, which he declines, opting instead to live a quiet life in Alicia's hometown. However, this peaceful existence is short-lived as they discover a vast conspiracy brewing within the empire.
Lewis meets Alicia's parents, Altorria and Premia Carfey, former adventurers themselves. While assisting Altorria with his work helping people, Lewis notices suspicious activity within the empire, linked to a group called the Sacred Republic Party, revealed to be agents of the neighboring Eurus Republic. Alicia also acquires a powerful skill, "Ancient Magic," further solidifying their resolve to stop the Sacred Republic Party's machinations.
The conflict escalates when the capital is attacked again, this time by the Sacred Republic Party directly, led by Lewis's old acquaintance, Hughes Blackness. Lewis and Alicia, along with the Adventurer's Guild, manage to repel the invaders, but Hughes is incapacitated, and Lewis is entrusted with a demon lord's egg.
The story then shifts to the Eurus Republic, where Lewis and Alicia investigate the empire's long-standing animosity with the republic, stemming from a war two thousand years prior. They encounter Flam Albane, an S-rank adventurer from the republic, who initially distrusts them but eventually warms to their character. Their investigation uncovers evidence that the Sacred Republic Party was being manipulated by a hidden mastermind. Simultaneously, a mysterious group known as the "Black Robes" emerges, exhibiting strength comparable to S-rank adventurers and acting erratically.
A major turning point occurs when the Eurus Republic's president, Vaize Claudia, declares war on the empire, falsely portraying them as aggressors. It is revealed that the Black Robes are actually S-rank adventurer Rest Nesleia, a minister in the Eurus Republic and a key figure in their long-standing plot. As the empire faces invasion, Lewis, Alicia, and Flam rush to the front lines. They confront Rest, who displays a fighting style similar to the legendary hero Elgar Chronois. Just as they are overwhelmed, Hughes Blackness reappears, aiding them with powerful magic. However, this entire conflict was a ruse orchestrated by President Vaize, who used the distraction to launch a devastating internal attack on the empire. Lewis and Alicia are forcibly teleported away by republican mages.
They find themselves in the Monster Realm, where they are guided by the former Demon Lord, Roan Vanitas, who was previously defeated by Lewis. Roan reveals the truth behind the two-thousand-year-old war: the empire's emperor possessed the "Absolute Treasure," a gem granting "Absolute Victory," and sought world domination. To counter this, foreign nations allied with the Monster Realm. The emperor then transferred the power of "Absolute Victory" to a young man named Elgar, who became the hero. Elgar, disillusioned by war, eventually sought peace and entrusted his power to a worthy successor through the Mirror Treasure, which eventually led to Lewis acquiring his "Unconditional Victory" skill.
Motivated by Elgar's legacy and the desire to stop the current conspiracy, Lewis, Alicia, and Flam undergo rigorous training with Roan. Lewis's skill evolves to "Absolute Victory," and they all significantly improve. Meanwhile, Emperor Solomon of the Saxendria Empire uses the "Absolute Treasure" to spread "Unconditional Victory" among his soldiers, intensifying their invasion of the republic.
Upon returning from the Monster Realm, Lewis and his companions seek an alliance with Vaize and Rest. Lewis defeats Rest in a fierce battle, earning their temporary cooperation. They then infiltrate the empire and engage in a direct confrontation. During this time, Lewis and Alicia are caught in a massive monster attack on the capital, which turns out to be a diversion for an assault on the royal castle. Lewis, realizing the castle's vulnerability and the potential for a hidden escape route, sends Alicia away for her safety and charges into the castle alone to confront the invaders, determined to fulfill his role as an older protector.
