At the Thyphlo Ruins, one of the stone slabs refers to a long dragon that protects the mountain of death.

How to Complete the Quest

Before you can complete this quest, you have to complete the Lightning Temple. Then go into your key items and summon Riju. The long dragon is on the east side of the island, and the end of the dragon is at 0204, 3123, 0174. Stand there and use Riju's ability to create a circle of lightning and shoot an arrow at something in the circle. This will reveal a chest.

Quest Reward

The chest contains 3 Topazes.