Erich von Rerugen

Erich von Rerugen began his career on the front lines (rising to the rank of first lieutenant), then served as a military attaché in the Allied Kingdom, before moving to staff work. At the beginning of the story, he is a major, head of the performance evaluation department in the General Staff's personnel department; it is he who awards Tanya the Silver Wings for the assault. Already in officer training, he witnessed her cruelty to junior officers and has considered her dangerous ever since. He is later promoted to lieutenant colonel and transferred to the Operations Directorate, where he works under Rudersdorf and Zettour. He inspects the frontlines, participates in operational planning, and supports (albeit with distaste) Tanya's proposals. Over time, he rises to the rank of colonel and higher (in later volumes, brigadier general). In later events, he even temporarily commands units, including elements of the 203rd Battalion. Despite his constant fear of the "Devil of the Rhine," Rerugen remains one of the Empire's most competent and reliable staff officers, whose career is closely intertwined with Tanya's successes.

Rerugen is a knowledgeable, conscientious, thoughtful, and highly professional officer. He is observant, analytical, and has a thorough understanding of the military's structure, earning high marks at the General Staff. Unlike most of his colleagues, he was one of the first (and perhaps the only one) to discern Tanya Degurchaff's true nature: not a "child prodigy," but a dangerous "monster in the guise of a little girl." At the same time, he is a humanist at heart—he genuinely sympathizes with the soldiers, painfully perceives losses, and does not share Tanya's utilitarian view of human lives as expendable. This creates a constant internal conflict: he understands Tanya's effectiveness and is compelled to support her operations for the Empire, yet he experiences deep discomfort, stress, chronic stomach pain, and nightmares just thinking about her. He is a patriot, loyal to the system, but remains a man of moral principles. Despite his fear of Tanya, he is the one who most often trusts her professionally and even champions her initiatives.

In the anime, he has dark (almost black or dark blue) medium-length hair with a distinctive long strand falling over the side of his face. His face is calm, coolly reserved, with soft yet stern features. He wears glasses with a light lower frame, which emphasizes his intelligent and analytical appearance. His gaze is often thoughtful or wary. He has a trim build, typical of a career officer. He usually wears the standard dark green/gray Imperial officer's uniform with red stripes, rank insignia (major → lieutenant colonel → colonel), and a cap. In the light novel and manga, his appearance is slightly different: short brown hair with a side parting, blue eyes, and a more "aristocratic" appearance without such an accentuated fringe. Overall, he gives the impression of a neat, intelligent, and slightly paperwork-weary staff officer.