A high school student and avid RPG player, Makoto Takatsuki, finds his life turned upside down when a bus carrying his entire class is caught in an avalanche. On the brink of death, the group is transported to a fantasy world ruled by powerful gods who grant each newcomer divine blessings, unique skills, and impressive stats. While his classmates receive powerful abilities befitting heroes, Makoto is given the opposite. He is labeled a weak apprentice mage with pathetic stats, skills far inferior to his peers, and a grim prognosis of only ten years to live.

Just as he is about to be abandoned by the established divine powers, Makoto encounters a minor goddess named Noah. Trapped within a dungeon and possessing no followers, she appears in his dreams and pleads with him to become her first believer. In exchange for his faith, she offers him her blessings and a divine weapon. With nothing left to lose, Makoto accepts her offer and embarks on a difficult journey to grow strong enough to rescue his new goddess. To overcome his limitations, he relies on his deep knowledge of RPG mechanics, training relentlessly and using his seemingly useless weak skills in unorthodox and clever ways.

The story takes place in a realm where the will of the gods dictates the fate of nations and adventurers. Makoto must navigate this world as a complete outsider, often shunned by the followers of more prominent deities. The main narrative arc of the series follows his initial struggle to survive and his unique pact with Noah, which sets him on a path to challenge the dungeon that imprisons her. Along the way, he encounters various companions, including powerful allies like the Crimson Witch, Lucy, as he gradually transforms from the weakest member of his class into a formidable force, proving that strategy and persistence can overcome even the most unfair of starts.