Hajime Nagumo is your average otaku at the age of seventeen until he and his classmates are mysteriously called upon to rescue humanity in a fantastical realm. Despite his peers' impressive fighting abilities, Hajime is scoffed at for his subpar transmutation skills that lack any offensive power. Through the perilous Great Orcus Labyrinth, Hajime is betrayed by a classmate, tumbling into an abyss. This only marks the start of his nightmare as he faces terrifying monsters and a string of misfortunes. Nevertheless, Hajime resolves to survive and return home, meeting Yue, a captive vampire whose yearning for freedom matches his own. Together with a few others, they embark on a treacherous journey, evolving from ordinary individuals into the world's greatest warriors.