Hajime Nagumo, an ordinary high school student, is transported to a fantasy world alongside his classmates as part of a hero-summoning ritual. While his peers receive powerful combat abilities, Hajime is granted the seemingly weak skill of transmutation, which allows him to manipulate materials. Ostracized and ridiculed for his perceived uselessness, Hajime’s life takes a drastic turn during a dungeon expedition when he is betrayed and left for dead by a classmate. Falling into the depths of the abyss, he encounters monstrous creatures and near-impossible challenges. To survive, Hajime undergoes a grueling transformation, both physically and mentally, as he adapts to the harsh environment.

In the labyrinthine depths, Hajime discovers ancient magic and technology, crafting powerful weapons and enhancing his abilities. His determination to return home drives him to grow stronger, but his experiences also harden his heart, making him more ruthless and pragmatic. Along the way, he forms a bond with Yue, a vampire princess imprisoned in the dungeon. Yue becomes his first ally and love interest, and together they escape the abyss. Their journey continues as they traverse the world, encountering other companions such as Shea, a rabbit-eared beastman with immense physical strength, and Tio, a dragon with a penchant for masochistic humor.

As Hajime and his companions grow stronger, they uncover the truth about the world they were summoned to. The gods of this realm are revealed to be manipulative beings who orchestrated the summoning of heroes to serve their own agendas. Hajime’s ultimate goal shifts from merely returning home to challenging the gods themselves, seeking to dismantle the system that exploits summoned heroes. Along the way, he confronts powerful enemies, including other summoned heroes who have been corrupted by their newfound power.

The narrative explores themes of survival, betrayal, and the cost of power, as Hajime’s journey transforms him from a timid teenager into a formidable force. His relationships with Yue, Shea, and Tio provide emotional depth, balancing the series’ darker tones with moments of camaraderie and humor. The story also delves into the moral complexities of Hajime’s actions, as his ruthless methods often clash with the ideals of his classmates and the world’s inhabitants. Through its blend of action, fantasy, and character development, the series presents a tale of resilience and defiance against overwhelming odds.