The story begins with Chris Dresscode, a former Japanese salaryman reincarnated as the third son of the Dresscode Viscount family, reluctantly accepting his new role as heir. His two older brothers have abandoned their titles to become mathematicians in the Royal Capital, leaving Chris, who yearns for a slow life, to inherit. He is constantly overseen by Yuris, his beautiful, silver-haired maid chief, who is much younger than she appears (late teens to early twenties). Yuris, a highly competent and seemingly sadistic woman, has subjected Chris to ten years of "education" (which Chris perceives as torture) and effectively runs the entire household, holding all real power. Despite Chris's protests, Yuris forces him to accept the viscountcy, emphasizing his minimal education has prepared him for the role.
Chris and Yuris embark on a long, uncomfortable journey to the Royal Capital for the investiture ceremony. The Dresscode territory, a poor transit hub surrounded by powerful noble houses (Alcala Marquisate, Piazzon Frontier Count, Orar Duchy), has decent internal roads but terrible external ones. The ceremony itself is shockingly brief and informal. Yuris reveals that this is due to the Dresscode family being looked down upon, and more critically, the Royal Family's own weakness. The King is embroiled in internal power struggles, lacks control over the feudal lords, and is on the verge of collapse, foreshadowing an era of war. Chris realizes his family is in grave danger, prompting Yuris to offer a rare, gentle promise of unwavering loyalty.
Chris then receives the Dresscode family's "treasure," a small ring that grants magic. He discovers his family's magic allows him to create stones, but with severe limitations: only within arm's reach, up to one meter in size, and creating many or heavy ones causes fatigue. His father only used it to maintain roads. This "useless" magic pales in comparison to the formidable abilities of neighboring nobles, such as the Alcala Marquisate's wind control, the Piazzon Frontier Count's five-sense enhancement, or the Orar Duchy's time manipulation. Realizing their vulnerability, Chris and Yuris decide they must acquire fighting power, which requires substantial funds.
To generate income, Chris introduces modern-day games like Reversi to the Sazaby Merchant Guild. The shrewd merchant, Sazaby, agrees to a partnership where Chris uses his magic to mass-produce the game pieces, ensuring authenticity and eliminating material costs, in exchange for 40% of the profits. Chris also introduces Mahjong and playing cards. Next, Chris and Yuris visit rural villages to introduce the Norfolk four-field system and discover a "poisonous" plant that grows abundantly: potatoes. Chris demonstrates how to cook them, proving their edibility and deliciousness, convincing the villagers to cultivate them.
Using the profits from games and the newly developed distillation technology (for perfume and liquor), the Dresscode family rapidly accumulates wealth. Chris implements "Rakuichi Rakuza" (free markets) and abolishes checkpoints, leading to a population boom and increased tax revenue. However, this growth overwhelms the existing administration and leads to a surge in crime, particularly in newly formed slums. The private army, led by the muscular Macbeth, struggles to maintain order. A month into this crisis, Yuris, fed up with the chaos, returns to her family home. Chris, exhausted and desperate, is overjoyed when she finally returns, admitting his dependence. Yuris brings with her her older brother, Hal, a former high-ranking royal civil official, and her younger brother, Zion, a genius design engineer. Both are from the prestigious Heart Viscount family, known for their Spartan education, but left their previous positions due to political infighting and incompetent superiors, respectively. Yuris herself, despite her exceptional talents, was only accepted by the "unconcerned, pride-less Dresscode Viscount family" due to her challenging personality.
With Hal managing the police and cleaning services, and Zion overseeing ambitious water management projects (including breakwaters, waterways, and future windmills for land reclamation), the slums disappear, and order is restored. Chris, though overworked, contributes by using his magic to create massive amounts of stone for Zion's projects, saving material costs. The Dresscode Viscountcy, once poor and overlooked, has transformed into a rapidly developing and wealthy territory, albeit one still heavily reliant on Yuris and her talented siblings, as Chris reluctantly embraces his role as an active lord.
