In a world where each person receives a single divine blessing known as a skill, Ard is a D-rank adventurer whose ability, Shrink, appears to do nothing more than make objects smaller. This seemingly weak skill has made him a perennial porter and pack mule for low-ranked parties, but Ard has deliberately cultivated this humble image. Every time a party he joins rises from D-rank to C-rank, he utters his trademark phrase, I'm leaving the party, collects his severance pay, and promptly blows it all on drink, feasting, and debauchery. He wakes up hungover, repeats the cycle, and asks for nothing more than an easy life fueled by cheap ale and loose coin.

Ard's freedom that borders on squalor is shattered when he inadvertently catches the attention of Alistera, the saintess of the current era's strongest hero party. After witnessing his true combat potential during a monster hunt, Alistera becomes relentless in her recruitment efforts. Desperate to shake her off, Ard throws out an absurd condition: he will join the hero party only if she marries him. To his utter shock, Alistera accepts on the spot, and Ard finds himself suddenly and unwillingly thrust into a marriage with a beautiful, pious saint and a position as porter and swordsman in the party destined to save the world.

Despite its unassuming appearance, Ard's Shrink skill is far from weak. He secretly understands that it operates on a conceptual level, capable of compressing space, time, and even the fundamental properties of objects and creatures. His deliberate underperformance is a calculated strategy to avoid glory, promotion, and the burdens of heroism. The hero party itself is composed of distinct personalities: the earnest and competitive female hero Karen, who initially challenges Ard to a duel to test his worth; the elderly sage Randolph, who quickly becomes Ard's drinking buddy and confidant; and Alistera herself, whose genuine kindness and growing affection slowly chip away at Ard's cynical detachment.

The story unfolds through several major narrative arcs. After Ard's forced recruitment and marriage, the early chapters focus on his adjustment to domestic life with Alistera and the friction with the hero party, including a decisive duel with Karen that exposes the true depth of his abilities. The party then embarks on a quest to subdue the demon lord Grimzeed, venturing into a deep dungeon where threats escalate rapidly. In the dungeon, Ard becomes separated from the group and encounters a mysterious fox-eared girl named Kurama, who is actually a four-thousand-year-old yokai known as the White Ice Fox. His promise to protect her, made in ignorance of her true power, leads to an unlikely alliance.

As the party delves deeper, Grimzeed's lieutenants appear, and the demon lord himself eventually confronts the hero team. When Ard is absent from a critical battle, Grimzeed uses a skill called Theft to drain the powers of Karen and Randolph, leaving Alistera in mortal danger. Ard returns in the nick of time, using his mastery of Shrink to turn the tide. However, even after this victory, new and even more formidable threats loom on the horizon, forcing Ard to confront his desire for anonymity with the reality that his power may be the only thing standing between the world and annihilation. The series balances over-the-top comedic escapades with moments of genuine action and the gradually deepening relationships around a protagonist who desperately wants nothing but a quiet, hungover morning.