Unlock: Use Franklin, Complete Three's Company
Requirements:
Silent Snapper – Take a pic of the princess without any alerts.
Royal Drag: Take a pic of the princess purchasing drugs.
Head to Mirror Park to reach the marker. Go to the left of the store and find the trash bin. climb up the roof using it, then sneak into the drug dealing. Take a pic of the money and drug exchange. Then send the file to Beverly afterwards.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art.