统一历1926年。 谭雅·冯·提古雷查夫少校所率领的帝国军第二〇三航空魔导大队, 在南方大陆发起攻打共和国军残党的战役。 他们期待着凯旋休假,但在本国等待着他们的却是参谋本部的特命。 命令称“联邦国境附近有大规模动员的征兆”。 面临新的巨人的觉醒,不顾一切的帝国军自然地将战果扩大…… 与此同时,联合王国主导的多国籍义勇军踏入了联邦内部。 敌人的敌人即是朋友。 被国家理性所引导,迎来多舛命运的他们之中,有一位少女。 玛丽·苏准尉。 她为了向杀害父亲的帝国讨回正义,而拿起了枪。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 salary men, reborn as a little girl after angering a mysterious being who calls himself God. This little girl, who prioritizes efficiency and her own career over anything else, will become the most dangerous being amongst the sorcerers of the imperial army.