http://www.amazon.com/Psi-Another-Day-Fighter-Academy-ebook/dp/B00BRAFRTG
Sixteen-year-old Rinnie Noelle has to deal with the routine headaches of any ordinary teenager attending a dysfunctional school—name-calling, humiliation, the joy of being a total outcast. Algebra.
But Rinnie is far from ordinary. She's a Psi Fighter, a protector of the innocent, fiercely skilled in the Mental Arts. Which comes in handy when she has to don her mask and armor to take down a vicious criminal, but is totally useless at school against the drug dealing bullies, who, by the way, she could totally mop the floor with. But mopping said floor with said bullies would give away the secret of her true identity. Once that's out, the Walpurgis Knights, deadly criminals from her past, would hunt her down, torture her, and learn the identities of the other Psi Fighters. The Knights are like the bad guys plus, like super villains on a steady diet of prune juice and fiber. They are just miserable people. When Rinnie learns that they have sent their apprentice to her school to find her, she decides to expose his identity before he uncovers hers. She just has to figure out who he is.
Aided by the Dweeb League, a band of oddly shaped, politically imperfect outcasts, Rinnie sets off on a journey to capture the apprentice, only to find that the man who sent him is the one person she wants to forget—the man who tried to kill her ten years earlier.