From Tarot Cafe:
Suyun's parents died when she was little. She is raised by a too-soft "Bro" and a money crazy sister that sends her to part time jobs by screaming each and every day. The only money she is allowed to have and spend is the money she earns; part of the money she earns, that is. So she works 24 hours a day- during morning she works as a student while during night she works as a par-time job girl. But she doesn't think that is enough... That is why she secretly works as "Guardian Angel", one who defeats those who have bullied the weaker. For a price, that is. What will happen when Suyun meets a real angel- one who has been banished from paradise?