Youjo Senki

On the front lines of the war, there is a little girl. Blond hair, blue eyes, and porcelain white skin, she commands her squad with lisping voice. Her name is Tanya Degurechaff. But in reality, she is one of Japan's most elite salarymen, reborn as a little girl into a world of magical warfare after angering a mysterious being who calls himself God.
Tanya resolves to ascend the ranks of her country's military as it slowly plunges into world war, with only Being X proving to be the strongest obstacle in recreating the peaceful life she once knew. But her perceptive actions and combat initiative have an unintended side effect: propelling the mighty Empire into becoming one of the most powerful nations in mankind's history.