The Ghost (2004)

Min Ji-Won suffers from amnesia caused by an accident almost a year ago. After the accident, Min Ji-Won is a shy person. Prior to the accident, Min Ji-Won was the leader of a gang of four girl bullies. Through pictures, Min Ji-Won learns about the three other members and she wants to learn what happened to them. While Min Ji-Won attempts to unravel the mystery, her former friends are killed one by one.