Fascinated by the profound lack of faith shown by a specific salaryman as he took his final breath, a deity referred to only as "Being X" reincarnates him into a magical, war-torn world to test his resolve. Under these new circumstances, Being X assumes that if the man falls victim to unending suffering, he will appeal to the heavens for help. Reborn as a young girl named Tanya Degurechaff, the former salaryman swiftly applies his past experiences and enlists in the military of his country, the Empire. Despite her childlike appearance, Tanya possesses immense potential; her exceptional aptitude for strategic and magical combat enables her to rapidly climb the ranks and consistently guide her nation to miraculous victories in the ongoing conflict. Nevertheless, she pursues all of this with a single goal: to remain in the rear, far from the war zone, thereby directly defying Being X's intentions. However, as Tanya attempts to evade Being X's influence, she soon realizes that even with her genius, there are scenarios that a human cannot surmount without divine intervention.