The man who can singlehandedly broke the stalemate of the war was called “The Empire’s Strongest Magician”. 
 Mowing down his enemies with tremendous magical power, as if a “demon” incarnate, an existence feared by his own allies.
 [— — Why do I look like this?!?]  
 For some reason the man’s appearance was that of a young dark elf girl. 
Even though [God] granted him the strongest magical power and the ability to read people’s minds, God thought that was boring, so the man was reincarnated as a girl. 
This is the chronicles of a perfect corporate s*ave becoming a dark elf and the process in which he climbs his way up in a parallel world.