Take the path left to enter a room with enemies guarding a blue Renan chest containing 14100 Gald. Unfortunately, you can't cross the bridge right now, so go through the door into the next area, the Main Tower. The story marker is directly to the north and a bridge is to the right. Once you're in Del Fharis Castle, remember to have Law on your team to beat up the Guards! You begin at the Central Entrance Plaza 1F.