The Onryo

Quarter-Finalist for the 2011 Amazon Breakthrough Novel Award.
 
Japanese teenager Chikara Kaminari, while heartbroken by the death of her mother, inherits a strange black ring. Her mother’s will tells her to share it with her best friend, Renka, and a socialist student, Gen, so that they can save the world from political fanatics. Guided only by cryptic clues yet honor-bound to obey her mother, Chikara does as she’s told.
 
As the three develop extraordinary abilities, including emotional manipulation and control over darkness, they set out to uncover the origin of the ring and its connection to their mind-controlling rival, Michiko. Their destiny becomes clearer as Michiko’s power grows beyond her control, setting a classmate on a murderous rampage. As dangerous extremists appear, seeking to use the ring’s power to force their political views onto all of humanity, Chikara and her friends must put aside their partisanship and become the heroes they were destined to be.