Espers are feared and treated like criminals, used for military purposes to fight against monsters known as the Sinners. Princess Misaka Mikoto's lavish life is turned upside down when she is found to be an esper herself. In order to survive, she has no choice but to adapt to an unknown world that hides dark and terrible secrets.

A strange virus suddenly spread more than a thousand years ago, wiping out most of humanity by changing them into mutants called Grimm. Many lost their lives or their sanity, but some gained strange powers and thrived in the new world. An infected Yang sets out to seek a cure and discovers some unsettling truths along the way…