Started out very promising, with excellent world building based on early 20th century China and a good underdog character who thinks outside the box. But then the main character turns into a sullen, whiny, genocidal monster who sees the entire world in black and white, ignoring the abuse she receives from her own allies even as she ceases to view the enemy as human. The really dark parts, which are based on actual history, felt shoehorned in as a lazy way to show just how bad the enemy was.