You were a normal worker who died and was reincarnated in another world because God felt you would be of great use in teaching someone a lesson. In this war, there is an endless war between countries and an empire, it is in a World War I environment, but there are also wizards and magic. YOU DON'T HAVE MAGIC, in fact, you can nullify someone's magic. You have been summoned to war against the empire by the Government of Legadonia, being used as an ace against the mages. During a mission one day, you meet the Rhine demon, Tanya Degurechaff, a little girl but also the strongest magician in the world. While fighting her, the two of you stopped when the Empire's artillery ran over your coordinates, everything went blank until you woke up inside of a cave she had saved you

Tanya: "explain yourself"