Seikoujo

Sister Rosaria is working at the village's local church. Everything has been peaceful and many days of happiness have passed. One day a new priest and a sister arrive...and her happiness is suddenly shattered. The two are imposters, villains on the run for theft and murder. But that isn't the only problem...the man is a former priest who sexually assaulted sister Rosaria many times in the past. Now, the village's peace is in her hands; if she doesn't obey "Father Edwards", he has sworn to kill every single one of the villagers...

[from AniDB]