Chapters 3-12 of the light novel detail the immediate aftermath of a major battle against the cult "Chaos Evil" and the subsequent political and personal developments for the protagonist, Yuto Amakusa, and his companions.
The narrative begins with Yuto, a black-haired boy in white robes, finding himself at a royal ball, a stark contrast to his adventuring life. He is joined by Waltrode, a beautiful, golden-haired knight who is a member of his adventuring party. Waltrode, who Yuto affectionately (and annoyingly to her) calls "Val-ko," reveals her new status: she has been granted a territory and a noble title, becoming Countess Waltrode of Silvermarch. Her primary motivation is to manage this new domain, but she admits to a significant flaw: illiteracy and a lack of academic knowledge, making her a "brainy musclehead." She asks Yuto to become her secretary, a request he initially misunderstands as a romantic proposal before clarifying it as a request for his assistance in managing her lands.
The story then flashes back five days to the climactic battle in the capital city, Sejour. The "Chaos Evil" cult, wielding the "Veil of Nothingness," launched an aerial assault with their obsidian fortress, the "Black Demon Fortress," threatening to revive the "Spiral of Despair," a force that could reduce the world to nothingness. Yuto, along with Waltrode, the rock giant barbarian Exile, the elven scout and archer Larshia, the high priestess of magic and death Alpatria, and the esper girl Yona, infiltrated the fortress. They confronted the cult's leaders, the Triade, and the fire spirit prince Il-Kanjuar, who served as the core for the ritual to unleash the Spiral of Despair.
During the battle, the adventurers demonstrated their formidable skills. Larshia swiftly eliminated one of the Triade with precise arrow shots. Exile proved his strength by defeating elemental spirits summoned by the Triade. Yuto, a powerful wizard, used his knowledge of Earth and elemental magic, as well as his unique ability to manipulate magic, to counter the cult's forces. Waltrode, wielding her holy sword "Divine Subjugator," fought valiantly against Il-Kanjuar. The Triade revealed their nihilistic philosophy, aiming to return the world to a state of "Origin" by destroying it.
A turning point occurred when Il-Kanjuar used a spell to banish Yuto's companions to another dimension. Yuto, revealing himself to be a Japanese exchange student named Yuto Amakusa, used his ultimate spell, "Great Wish," powered by a valuable diamond and a torn spellbook, to bring his friends back. The battle resumed, and despite their preparations, the adventurers were overwhelmed by Il-Kanjuar's "Inferno" attack, which was revealed to be a curse rather than mere fire. Alpatria, a high priestess, healed them with a divine miracle. Yona, a powerful esper, then used her abilities to defeat hidden dark elf assassins. Yuto countered further threats with his "Seven-Light Barrier," effectively trapping enemies.
Waltrode then engaged Il-Kanjuar in a fierce duel, ultimately defeating the fire spirit prince. The cult's artifact, the "Ebony Orb of Frenzy," exploded, threatening to destroy the entire fortress and the capital below. Yuto, using his ultimate counter-spell, "Magic Deconstruction," contained the explosion, saving the city. The adventurers emerged victorious, but exhausted.
Following the battle, the group received divine rewards. Yuto, upon questioning the gods about his summoning, learned it was a mere coincidence, though he was granted a cryptic warning about a significant decision in a year. Waltrode, seeking practical benefits, requested a fortress for her territory.
The narrative then shifts to Yuto's preparations to fulfill Waltrode's request. He, along with Alpatria and Yona, travels to the former village of Falv, now the site of Waltrode's granted territory. To their surprise, a magnificent fortress has miraculously appeared overnight. Yuto, using his vast magical knowledge and resources, including a valuable gem, begins terraforming the land according to a plan devised with the great sage Vainamainen. He creates a city layout, including a river diversion and the construction of a defensive wall using magic.
Meanwhile, Yuto and Waltrode visit the dwarf mining town of Maintz. They discover the town is in decline due to "Quartz Beasts" that corrupt the mines and "Giants" that inhabit the coal deposits. Yuto proposes a plan to clear the monsters, utilize the corrupted quartz by creating a new alloy called "Crystal Iron" with the help of the dwarves, and establish new industries. He offers substantial financial backing and a generous wage to incentivize the dwarves to relocate and work on the new city project. Waltrode, in turn, participates in a drinking contest with the dwarf clan leader to secure their agreement.
Yuto then travels to the port city of Hardentum to address its issues. He confronts Bruno Exdero, the head of the dominant Exdero Trading Company, who has been exploiting the city and was complicit in the death of Regina Niebes' parents. Yuto, using his knowledge and resources, exposes Bruno's corruption, arranges for the removal of a sunken pirate ship blocking the harbor, and offers Regina a deal to help her company rise again, effectively creating a rival to Exdero. He also proposes a new tax system based on profit rather than a fixed rate.
The story concludes with Yuto and Alpatria returning to the fortress in Falv. Yuto, despite his exhaustion, continues his work on land development, while Alpatria, who has some experience in temple work, advises him to rest. Yuto, however, is driven by his responsibilities and the desire to build a prosperous territory for Waltrode, even as he grapples with the complexities of his new life and the lingering memories of his past.
