Jeffrey-kun, a young noble of the Mailstar lineage, is groomed to continue his family’s knightly legacy despite his frail physique and inept combat skills. His mother, Josephine, enlists mercenary mages Lina Inverse and Naga the Serpent to train him, determined to cement the family’s prestige through his ascension to the royal guard. Jeffrey’s physical limitations—clumsy swordsmanship, frequent falls, and self-inflicted knockouts—clash starkly with his unshakable belief in his imagined talents, a delusion nurtured by Josephine’s relentless praise.

Josephine’s covert overprotection defines Jeffrey’s reality. She shadows him under a burlap disguise, violently silencing detractors while remaining undetected. Jeffrey dismisses her interventions as luck, convinced his accidental triumphs—like scattering foes via tripping or surviving ambushes—validate his false prowess. This cycle persists until a staged bandit mission unravels: real outlaws ambush Jeffrey, exposing his incompetence as he disarms himself and collapses. A fleeting spark of competence emerges when Josephine is stunned; Jeffrey nicks the bandit leader’s arm, shocking observers. Later, facing a warlord’s forces, Josephine exposes her husband as the conflict’s hidden architect, resolving the crisis herself.

The family reconciles their tumultuous roles, but Jeffrey’s growth stagnates. His unwavering delusions and Josephine’s extremes sustain his role as a comedic contrast between inflated self-image and hapless reality, underscoring the absurdity of their dynamic.