An entire bus of people is summoned to another world to become heroes and defeat the Demon Lord. One of them, Souma Nagi, is immediately suspicious of the king’s vague promises and poor working conditions. Having grown up neglected and exploited in part-time jobs, he refuses the hero role, leaves the palace, and decides to live a relaxed life on his own terms. In the process of being summoned, Nagi has gained a unique skill called Ability Restructuring (Skill Structure), which allows him to dismantle, rearrange, and completely rewrite the skills of himself and others.

Soon after setting out, a mysterious collective consciousness of the demon race named Ashtarté urges Nagi to rescue the last surviving demon, a dark‑elf slave girl named Cecil Pharott. He buys Cecil from a slave trader and immediately uses his skill to give her extremely powerful abilities. Cecil becomes his devoted partner, calling him “master,” and the first of many “cheat wives.”

As Nagi and Cecil travel, they encounter and add more women to their group. Each girl is initially in a desperate situation that Nagi’s skill can resolve. Rita, a high priestess of the Iturna order and a beastkin, is fighting a giant monster when Nagi meets her again; he restructures her skills to make her a formidable fighter. Aine, a maid‑like woman whose memories have been stolen, joins after a confrontation with a reincarnator named Tanaka Koga. Leggy is a sentient magic sword with a lazy and demanding personality, who requires entertainment in the form of Nagi’s harem before she agrees to cooperate. Raffiria, an elf with a curse that brings misfortune to everyone around her, has her harmful skill replaced, finally allowing her to make friends. Iris, a priestess of the Sea Dragon, eventually becomes bound to Nagi through a soul‑bonding ritual to save her people. Later additions include the mysterious knight candidate Catras and others.

The story unfolds across several narrative arcs. After leaving the capital, Nagi registers as an adventurer and gets involved in a quest to acquire the magic sword Leggy. Later arcs deal with false demons threatening towns, the effects of skill restructuring causing side effects like uncontrollable affection, the retrieval of Aine’s lost memories, and the elven curse. A major turning point is the Sea Dragon arc, where Nagi is unexpectedly identified as a legendary “Sea Dragon Hero” and must resolve a conflict between Iris and her troublemaking brother Noël. Subsequent arcs take the group into the Mist Valley, where they confront a self‑centered countess and uncover secrets about a heavenly dragon.

Throughout, Nagi’s overriding goal is to avoid dangerous quests and live a peaceful, comfortable life. However, his growing harem and his involvement in the problems of others keep pulling him into bigger adventures. The skill restructuring itself has a sensual side effect for the recipient, frequently leading to suggestive scenes. The manga blends action, fantasy, comedy, romance, and ecchi elements as Nagi continues to acquire new wives and upgrade their abilities.