Three parts needed: Mystery Part Alpha, Mystery Part Beta, Mystery Part Gamma
Once all three parts have been located. Take them to the research lab in Jibral Castle and speak to the research officer.
Mystery Part Alpha
Location: Mural Town
** Automatic pickup**
Mystery Part Beta
Location: Ancient Factory, at the top of the winding slope there are some Double Lancer stone statutes. One by one they will unfreeze. Defeat them all for a chest to appear.
Mystery Part Gamma
Location: Upper Mecha Base 1F (in a treasure chest by the lift)
Find Upper Mecha Base on disc 3, southern most yellow plus sign. By the lift on the 1F.