Middle school student Fukuo Tsumugi is a genius tailor who runs his own brand in the human world. One day he is suddenly summoned to the Abyss, a desolate otherworld populated by monsters. There, he is granted the power of magic sewing, which allows him to transform any material—fire, hail, even the environment itself—into thread and cloth. Tsumugi is tasked with using this ability to make clothes for the monsters, who suffer from extreme climates and lack proper garments. The Abyss has no clothing culture, and the harsh volcanic, frozen, and wetland regions make life unbearable for its inhabitants.

Tsumugi begins traveling the Abyss with companions he meets along the way. Fari, a wyvern and the king of this world, was the one who summoned him and acts as a caretaker for the group. Keru, a cerberus, joins them with her sisters Bero and Su; she is curious and easygoing. Later they encounter Homura Ran, a legendary salamander who was freezing in the forest, and she becomes a party member. Together they journey from region to region, solving the monsters' problems by designing and sewing magical clothing that not only protects them from the elements but also brings them hope and joy.

The story progresses through several major arcs. Early on, Tsumugi helps a variety of monsters by creating heat-resistant garments from fire, waterproof insulation from hail, and other custom outfits using his sewing power. In the second volume, Tsumugi meets Homura and learns that her forest friends are dying from an unprecedented cold wave. He sews special coats that save them, deepening their bond. The third volume introduces a greedy monster who kidnaps Tsumugi to monopolize his tailoring abilities. After a tense pursuit through swamplands, the group escapes and moves on to new territories. In the fourth volume, the party arrives at a floating Sky School. Tsumugi establishes a clothing club there, solving problems for students and teachers alike, while an irritated girl watches his activities with suspicion. The journey continues as Tsumugi uses his craft to heal and empower the creatures of the Abyss one stitch at a time.