Saga of Tanya the Evil

This series follows a ruthless salaryman reincarnated as a young girl in an alternate-history version of WWI, where magic is used as a weapon. Tanya is a brilliant, cold-blooded strategist who rises through the ranks of the military while constantly battling against the 'Being X' that put her there. It is a fascinating look at military bureaucracy, the ethics of total war, and the sheer absurdity of conflict. It is a unique, dark, and often darkly comedic take on the war genre that stands out for its protagonist's sheer ambition.