Optional: Before entering, talk to Sama Gohjima, who is standing before the entrance. She will tell you the minister of the Orastery is in the lab below, and that to get there you should check the walls carefully.
Upon entering the Ruins, you will be in the Lily Tower (Map 1). Go down the stairs until you come to the main room.
Circle around the room and look for the crack in the center of the south wall at (H-9) (if you see dirt instead of brick floors, you've taken the wrong cracked wall opening).
Enter and go left. Click on the Gate: Magical Gizmo at (I-9) to watch another cutscene with the Minister.
Next, search the six different Ancient Magical Gizmos (which are spread out in the room before the hallway to the cutscene) until you find the Cracked Mana Orb. The Cracked Mana Orb will be obtained at a randomly selected Ancient Magical Gizmo.