In a world where magical ability is strictly categorized by numerical scores and combat efficiency, sixteen-year-old Kaito has always been labeled a failure. At the prestigious Celestia Academy, his magic output is so low and unstable that his practical training scores are negative, making him a target for ridicule and the constant threat of expulsion. While his peers are honing powerful elemental attacks and complex defensive wards, Kaito discovers his magic only seems to manifest reliably in one specific, quiet context: when he is trying to heal a wilting plant, soothe a frightened animal, or fix a broken teapot.

The story shifts when he crosses paths with Towa, a reclusive senior student who was once hailed as a prodigy before a mysterious accident crippled her mana circulation. Now unable to cast high-level spells without immense pain, she spends her days in the neglected greenhouse at the edge of campus. Recognizing a strange resonance between his residual magic and the delicate life energy she studies, Towa agrees to train him—not to be a powerful mage, but to master the art of "small magic." Their goal is to prove that magic intended for comfort, restoration, and daily life is not a weakness but a specialized and vital discipline.

The setting is Celestia Academy, a sprawling fortress-like school built upon the ruins of an ancient city. The academy’s culture is dominated by the competitive "Grand Casting" ranking system, where students duel to climb the leaderboards. In contrast, the forgotten "Familiar's Wing" and the overgrown Lumina Garden become Kaito and Towa’s sanctuary. The world’s underlying lore reveals that magic itself originates from an ancient pact with nature spirits, but modern combat magic has violently disrupted this balance, causing "mana rust" to spread across the land—a decay that feeds on aggressive spell-casting.

The narrative unfolds in distinct arcs. The first arc, "The Zero-Point Student," establishes Kaito’s daily humiliation and his accidental discovery of his affinity for mending magic when he saves a class pet. Here, he meets Towa and learns the basic principles of "Weave Casting," a gentle method of threading magic through the natural mana currents of objects. The second arc, "The Greenhouse Pact," focuses on their secret training. Kaito learns to fix broken artifacts, enhance flavors in the school cafeteria’s food, and create temporary wards that calm emotional distress. This arc also introduces Lilia, a top-ranked combat mage and Kaito’s childhood friend, who is torn between her ambition and her worry that Kaito is wasting his potential.

The third major arc begins when a violent mana storm, a byproduct of the academy’s intense competitive casting, threatens to destroy the Lumina Garden and the fragile ecosystem around the school. The standard combat magic of the instructors and top students only makes the storm angrier, feeding its destructive energy. Forced into action, Kaito and Towa demonstrate that only their gentle restoration magic can "untangle" the storm’s chaotic energy. They succeed, but their unorthodox methods draw the attention of the Headmaster, who reveals that the ancient pact is breaking and that the world needs "Feel-Good Mages" to repair the damage before aggressive magic consumes everything. The synopsis ends with Kaito accepting his place not as a failed combat mage, but as the first student in a new course of study dedicated to magical restoration, setting the stage for a journey where the greatest power is not the ability to destroy, but the skill to heal and nurture.