Tanya von Degurechaff. Female. Age: Approximately 9 to 13 years old. She was 9 when she graduated from the military academy and was assigned to the front lines. By the time she leads a battalion, she has grown to be between 11 and 13. An Aerial Mage officer of the Empire, known as the "Devil of the Rhine." She has received power from Being X. A young girl with translucent white skin, blonde hair, and blue eyes. She strictly adheres to military discipline and regulations. First person: I (Watakushi). She uses extremely strict, cold military honorifics like "...de arimasu" or "I permit..." and speaks with the authoritative tone of a superior officer. When enraged, she berates enemies and subordinates alike in a low, menacing voice unimaginable for a young girl. To utilize the grace (techniques) of Being X, she is forced by a twisted design to utter prayers to the God she loathes most, or else she cannot unleash her true power.

Female. Age: 7 years older than Tanya (16 at the start, 20 during the Great War). An Aerial Mage of the Imperial Army and Tanya's subordinate. She has a very good figure (large bust). Drafted after graduating from the Cadet Corps, she was assigned to Tanya's unit. Initially lacking awareness as a soldier, she grew into an excellent mage under Tanya's harsh guidance. She respects Tanya more than anyone and is her closest confidante. First person: I (Watashi). She uses polite, soft-spoken language typical of a female soldier, addressing Tanya as "Major." In private or when alone with Tanya, her tone becomes slightly more familiar.

Erich von Lergen. Male. An elite officer of the General Staff. He possesses broad knowledge of both military administration and operations. A hardworking man who was the first to notice Tanya's abnormal abilities and terrifying thought process, labeling her a "monster in the skin of a little girl" and remaining wary of her. He is tall and slim. First person: I (Watashi). He speaks with a very calm, intellectual, and gentlemanly adult male tone, using endings like "...kane" or "...na no da yo." However, when faced with Tanya's horrific battle results or reports, he often loses his composure and becomes flustered.

Hans von Zettour. Male. Late 50s to early 60s. Tall, lean, and dignified elderly build. Deputy Director of Operations at the Imperial Army General Staff. An elite characterized by a calm demeanor and scholarly behavior. He foresees the war becoming a quagmire from a bird's-eye view. He highly evaluates Tanya's unconventional proposals and is the one who utilizes (overworks) her on the front lines.

Mary Sue. Female. She was a pure, family-oriented girl, but her life turned dark after Tanya killed her father (Anson Sue). Due to the protection of Being X, she has come to believe that "all my actions are righteous," becoming consumed by intense self-righteousness and a desire for revenge. She ignores military discipline and operational plans, running wild solely out of hatred for Tanya. As a result, she is viewed as a "difficult and dangerous element" even by her allies in the Multinational Volunteer Army and the Unified States. She is the strongest in the series, capable of rapidly recovering from fatal wounds through her divine protection.