Orhun Dura, once a skilled swordsman, changed his class to enchanter to fill a crucial gap in the Hero Party led by his childhood friend Oliver. After the party gains fame, Oliver abruptly expels Orhun, claiming his abilities are insufficient. Orhun's former comrades mock him as a jack of all trades but master of none, a burden who held them back. In reality, the party relied heavily on the unique enhancement spells he developed, and the true reason for his dismissal involves political maneuvering within the guild.

Following his expulsion, Orhun decides to restart his adventuring career as a solo swordsman, the role he originally excelled in before sacrificing his own progression for the team's balance. He soon crosses paths with the Clodel sisters: Sophia, a rookie adventurer whose party abandons her to a horde of orcs, and Selma, her older sister and a renowned enchanter known as the strongest in the realm. Selma, who recognizes the sophistication of Orhun's magic, recruits him into her elite guild, the Night Sky Silver Rabbits. Initially hired as a temporary instructor for a party of promising but inexperienced rookies including Sophia, the hot-headed swordsman Logan Hayward, and the reckless but regenerative Caroline Inglaud, Orhun gradually proves that his diverse skill set makes him a uniquely powerful all-rounder rather than a master of none.

The story is set in a fantasy world where adventurer parties follow a rigid class system popularized by Selma's own theories. The world features a vast dungeon system, with the Great Southern Dungeon serving as a primary challenge for high-level parties. As Orhun trains his new students, the narrative explores several notable arcs. The early episodes establish his expulsion and his initial solo dungeon runs, where he effortlessly clears floors that gave his former party trouble. A major arc involves the Black Dragon incident, where Orhun must protect the rookies from a high-level dragon while also confronting a shadowy figure from his forgotten past. This arc forces him to fully embrace his original swordsman identity while integrating his enchanter experience, leading to a confrontation with the guild leadership where he presents his version of events. Another significant arc sees the Hero Party crumbling without Orhun's support, as their new enchanter fails to replicate his unique spells. Luna Flockhart, the Hero Party's healer who always respected Orhun, eventually leaves the disgraced group to join the Night Sky Silver Rabbits, bringing further insight into the conspiracy that led to Orhun's dismissal. The season culminates in an encounter with Shion Nasturtium, a figure from Orhun's forgotten childhood who suggests that his latent potential, sealed away by a mysterious spell, is beginning to resurface. A second season has been announced to continue Orhun's journey toward becoming the ultimate all-rounder and uncovering the truth about his sealed powers.