Tista, Vol. 1 by Tatsuya Endo

[Viz] Tista leads a dual life as an assassin and a university student. What price will she pay to save the people she loves? In New York City, the NYPD struggles to track down a serial killer known as Sister Militia, who has been targeting mobsters and other criminals in the Big Apple. No one knows who Sister Militia really is except a few residents of a Catholic orphanage. Her name is Tista… Tista leads a dual life as the grim reaper of New York City and a university student studying to be a teacher. With extraordinary eyesight allowing her to make long-range shots with unrivaled accuracy, she has come to be feared by the criminal underground. Tista knows she’s doomed, but can her feelings for a young man she just met bring her back from the abyss? And what will she do if he finds out who she really is?