Hajime Nagumo, an ordinary high school student, is transported to a fantasy world alongside his classmates as part of a summoning ritual to save the kingdom of Tortus from demons. While his peers receive powerful combat-related abilities, Hajime is granted the seemingly weak skill of transmutation, which allows him to manipulate materials. Initially dismissed as useless, Hajime is relegated to a supporting role and treated as an outcast by his classmates. During a dungeon exploration mission, he is betrayed and falls into the abyss of a treacherous labyrinth, presumed dead.

Surviving the fall, Hajime undergoes a harrowing transformation. Faced with monstrous creatures and near-death experiences, he uses his transmutation ability to craft weapons and tools, gradually becoming stronger. Consuming monster meat to survive, his body undergoes mutations, granting him enhanced physical abilities and a ruthless mindset. In the labyrinth, he encounters Yue, a vampire princess imprisoned for centuries. The two form a bond and work together to escape the dungeon. Over time, Hajime’s party grows to include other companions, such as Shea, a rabbit-eared beastman with immense physical strength, and Tio, a dragon-woman with a penchant for masochism. Each member contributes unique abilities and personal motivations, enriching the group dynamic.

As Hajime and his companions traverse the world, they uncover the truth behind the summoning of heroes and the kingdom’s hidden agendas. The story delves into themes of betrayal, survival, and the moral complexities of power. Hajime’s journey is marked by his evolution from a passive, ordinary individual to a formidable and pragmatic leader. His relationships with his companions, particularly Yue, are central to the narrative, providing emotional depth and moments of levity amidst the darker tones of the story.

The series balances action, world-building, and character development, exploring the intricacies of the fantasy world and its inhabitants. Hajime’s quest for a way back to his original world intertwines with the larger conflict against the demons and the machinations of the kingdom’s rulers. The manga adaptation captures the essence of the light novel series, presenting a visually engaging and cohesive narrative that appeals to fans of fantasy and adventure genres.