A little girl with blonde hair, blue eyes, and porcelain skin fights on the front lines of a brutal war set in a fantasy world. What others don't know is that she's a reincarnated Japanese office worker who, in his former life, had a ruthless desire to climb the corporate ladder in hopes of retiring to a cushy corner office. After death, Being X decides to give him one last chance to surrender and believe-and Tanya Degurechaff is born.

However, Tanya is as stubborn and coldhearted as she was in her former life. Furthermore, her goals remain the same-find a way to retire to a cushy life. Instead, she constantly finds herself being tested on the front lines of the most hostile situations because Being X is determined to win her over, at any cost. Both parties are equally stubborn, and could it be that both are equally evil?