Wearing the Saint Necklace, it has two usesl to keep your "ghost sense" from causing actual damage, and to actually exorcise spirits from your apartment. When wearing it in any other world besides the apartment, the screen will do its usual haziness when ghosts appear, but nothing more until the necklace breaks. Keep in mind that the necklace will break if you are confronted by ghosts for too long. Wearing the necklace and running to a possessed area of your apartment will cause the spirit to fight back, but if the necklace is not already broken, the spirit will lose and disappear. Keep in mind that you must have your apartment completely exorcised for the good endings.